New Methods ...
Topo Quantum Matter as a New State of Matter :
“Experiment is the only means of knowledge at our disposal. Everything else is (conceptual proposal) poetry, imagination” – Max Planck.
APS-Physics: https://absuploads.aps.org/presentation.cfm?pid=14503
NEW FORMS OF MATTER (beyond all forms of quantum Hall physics) : At the end of the 20th century, topology was discovered to govern quantum states of matter through the quantum Hall effects. In the early 21st century, this principle led to the discovery of Topological Insulators and Weyl Semimetals (beyond all quantum Hall or its later all 2D Chern incarnations) in bulk 3D solids, in which entirely new forms of topological quantum matter and new fermionic quasiparticles—helical-Dirac and Weyl fermions—were realized in bulk 3D solids experimentally observed through bulk-boundary correspondences, spin-momentum locking, helical spin-textures, helical and chiral edge states, Fermi arc quasiparticles, helical Cooper pairings (all beyond qunatum Hall physics and thus new..) etc defining a revolution in topology (thousands of bulk materials are topological! and our foundational experiments are cited 100,000+ times and included in many standard TextBooks by now). .. Advanced spectroscopy, which led to seminal discoveries of new phases of matter [Discovery Patent # US10214797B2] and new fermionic quasiparticles (Helical topological Dirac, Weyl fermions, and other topological fermions)...
Beyond the old quantum Hall measurement paradigm …
A New Paradigm: A Novel Method (see, invited review, Rev. of Mod. Phys. 82, 3045, 2010) for decisively measuring "topological invariants" led to the creation of a new continent of research with multiple groundbreaking discoveries, including topo. Dirac-Weyl fermions and more..
Indeed, Topo Insulator by itself is an incomplete story !! …
Only with the discovery of Topo Conductors (Dirac-Weyl and Nodal Semimetals), the basis set for the “Topo Materials Universe” (Topological Revolution) led to the completion (by the basis set) that now defines it. Our experiment started in 2004 and was completed in 2007 :
https://newscenter.lbl.gov/2017/04/14/how-x-rays-pushed-topological-matter-research-over-the-top/
Theoretical Discovery: Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class (Bi2Se3 class) with spin-polarized single-Dirac-cone on the surface (Hasan group)
Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class (Bi2Se3 class) with spin-polarized single-Dirac-cone on the surface (Hasan group)
https://arxiv.org/abs/0908.3513 (2009) [Submitted to Nature Phys in 2008 ]
Intrinsic fully bulk INSULATING 3D-Topo-Insulators (Nature Physics 2014)
https://online.kitp.ucsb.edu/online/lsmatter_c15/hasan/oh/17.html
Topological insulators, Helical superconductors and Weyl fermion semimetals: discoveries and outlook
https://iopscience.iop.org/article/10.1088/0031-8949/2015/T164/014001/meta
We use advanced Spectroscopy, Transport; Microscopy (STM/STS) and other methods in our research to probe quantum degrees of freedom.
Topological Invariants measured via Spectroscopy ..
What is NEW?
Unlike string theory, topological physics in lower dimensional condensed matter systems is an experimental reality since the bulk-boundary correspondence can be probed experimentally in lower dimensions. Recent experimental discoveries of non-quantum-Hall-like topological insulators, topological superconductors, Weyl semimetals and other topological states of matter also signal a clear departure from the quantum-Hall-effect-like transport paradigm that has dominated the field since the 1980s. It is these new forms of matter that enabled realizations of topological-Dirac, Weyl cones, helical-Cooper-pairs, Fermi-arc-quasiparticles and other emergent phenomena in fine-tuned photoemission experiments since such experiments directly allow the study of bulk-boundary (topological) correspondence. Taken collectively, we argue in favor of the emergence of ‘topological-condensed-matter-physics’ in laboratory experiments for which a variety of theoretical concepts over the last 90 years (Dirac-Weyl topology, negative-Dirac-mass, Dirac-monopole-Berry charge, Aharonov-Bohm phase, CHerring's exceptional points (modern Weyl node), Karplus-Luttinger theory (modern Berry curvature), SSH-chain, Jakiw-Rebbi and many foundational theories before 1970s – Topological theories are not new! ) paved the way for modern experiments on Topological Materials! (Materials are not new either)
What is new? Advanced Spectroscopic experiments that enable precise determination of “Topological Invariants” (see, for a review, RMP 82, 3045 (2010)
New Technique required beyond quantum Transport
Beyond quantum Transport
For Topo Insulators, 𝜎𝑥𝑦 (Transport) = 0; all 4 “Topo Invariants” that define them must be measured via Spectroscopy
See, Review, Hasan-Kane RMP 82, 3045 (2010)
Intrinsic fully bulk INSULATING 3D-Topo-Insulators (Nature Physics 2014)
Intrinsic fully bulk INSULATING 3D-Topo-Insulators (Nature Physics 2014)
https://online.kitp.ucsb.edu/online/lsmatter_c15/hasan/oh/17.html
Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class (Bi2Se3 class) with spin-polarized single-Dirac-cone on the surface (Hasan group)
https://arxiv.org/abs/0908.3513 (2009) [Submitted to Nature Phys in 2008 ]
APS-Physics: "Topological Invariants via Spectroscopy (New Methods)
APS-Physics: "Topological Invariants via Spectroscopy (New Methods)
Topo Invariants precisely define a New Topo State of Matter which can be precisely measured via Spectroscopic measurements (no transport or quantum Hall transport is needed). This invited talk at APS-Physics elaborates this NEW method which enabled discovery of many novel topological states of matter…
Fermi-Arcs: Discovery of Fermi-Arc (Dirac-string) states in Topo Metals..
Fermi-Arcs: Discovery of Fermi-Arc (Dirac-string) states in Topo Metals..
Science (2014)
A New Paradigm : A Novel Method (Rev. of Mod. Phys. 82, 3045, 2010) for decisively measuring "Topological Invariants"
A New Paradigm : A Novel Method (Rev. of Mod. Phys. 82, 3045, 2010) for decisively measuring "Topological Invariants"
A New Paradigm : A Novel Method (see, invited review, RMP 82, 3045, 2010) for decisively measuring "topological invariants" which led to the creation of a new continent of research (the field of topological materials) with multiple groundbreaking discoveries, including topo. Dirac-Weyl fermions, Fermi arc and more..
https://journals.aps.org/rmp/abstract/10.1103/RevModPhys.82.3045
Theoretical Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class (Bi2Se3 class) with spin-polarized single-Dirac-cone on the surface
Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class (Bi2Se3 class) with spin-polarized single-Dirac-cone on the surface
Theoretical Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class (Bi2Se3 class) with spin-polarized single-Dirac-cone on the surface
https://arxiv.org/abs/0908.3513
Intrinsic fully bulk INSULATING 3D-Topo-Insulators (Nature Physics 2014)
https://online.kitp.ucsb.edu/online/lsmatter_c15/hasan/oh/17.html
https://arxiv.org/abs/0908.3513 (2009) [Submitted to Nature Phys in 2008 ]
Topological Phases
Topological kagome ...
--
Weyl ...
New Methods ...
Unexpected and unpredicted novel (many-body, correlated) quantum phenomena in Topological Kagome Magnets & Superconductors:
Unexpected and unpredicted novel (many-body, correlated) quantum phenomena in Topological Kagome Magnets & Superconductors:
Experiments started in 2017, completed in 2017, Nature’18, NaturePhys’19, PRL’19, PRL’20, NatureCom’20a, NatureCom’20b, NatureCom’20c, Nature’20, NatureMat’21, PRL’21, Science’19, Nature’19, Nature’22a, Nature’22b, PRL’22, NaturePhys’22, NatureCom’22, NatureCom’23a, NatureCom’23b, NaturePhys’23, NatureCom’24a, NatureCom’24b, NatureCom’24c, NatureMat’24
Novel quantum phenomena in Topological kagome magnets and superconductors (Nature 2022) :
Single-Dirac-cone topology ..
Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class (Bi2Se3 class) with spin-polarized single-Dirac-cone on the surface
Theoretical Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class (Bi2Se3 class) with spin-polarized single-Dirac-cone on the surface
https://arxiv.org/abs/0908.3513
Intrinsic fully bulk INSULATING 3D-Topo-Insulators (Nature Physics 2014)
https://online.kitp.ucsb.edu/online/lsmatter_c15/hasan/oh/17.html
https://arxiv.org/abs/0908.3513 (2009) [Submitted to Nature Phys in 2008 ]
Early works on 3D-TI ..
--
Weyl topology
Discovery of 2D & 3D Topological Magnets :
Theory and Experiments : “In this talk I present our* theoretical and experimental works on 2D and 3D topological magnets in novel Weyl and Dirac materials building up on earlier result but including recent results "A three-dimensional magnetic topological phase" Ilya Belopolski et.al., arXiv:1712.09992 (2017); "Topological quantum properties of chiral crystals" Guoqing Chang et.al., Nature Materials (2018); "Topological Hopf and Chain Link Semimetal States and Their Application to Co2MnGa" Physical Review Letters 119, 156401 (2017); "Magnetic Weyl fermion semimetals in the R-AlGe family of compounds" Physical Review B (2018) and Jiaxin Yin, Songtian Zhang et.al., "Giant and anisotropic many-body spin–orbit tunability in a strongly correlated kagome magnet" NATURE 562, 91–95 (2018). *Guoqing Chang, Bahadur Singh, Su-Yang Xu, Guang Bian, Shin-Ming Huang, Chuang-Han Hsu, Ilya Belopolski, Nasser Alidoust, Daniel S Sanchez, Hao Zheng, Hong Lu, Xiao Zhang, Yi Bian, Tay-Rong Chang, Horng-Tay Jeng, Arun Bansil, Han Hsu, Shuang Jia, Titus Neupert, Hsin Lin, Jia-Xin Yin, Songtian S. Zhang, Hang Li, Kun Jiang, Bingjing Zhang, Cheng Xiang, Hao Zheng, Tyler A. Cochran, Daniel Multer, Guang Bian, Kai Liu, Zhong-Yi Lu, Ziqiang Wang, Shuang Jia, Wenhong Wang, Biao Lian, Benjamin J. Wieder, Frank Schindler, Di Wu, Titus Neupert and Tay-Rong Chang” *DOE/BES (DE-FG-02-05ER46200) and GBMF4547 (EPIQS initiative)
A Paradigm Shift ...
For Topo Insulators, 𝜎𝑥𝑦 (Transport) = 0; all 4 “Topo Invariants” that define them must be measured via Spectroscopy probing Bulk-Boundary correspondence directly :
See, Review, Hasan-Kane RMP 82, 3045 (2010)
APS-Physics lecture: https://absuploads.aps.org/presentation.cfm?pid=14503
This (𝜎(Hall) = 0) leads to New Physics: Beyond all forms of quantum-Hall-like physics and their modern descendants
Non-QuantumHall-like Topo Matter
Non-QuantumHall-like Topological Matter configuration options
Hasan, M. Z., Xu, S.-Y. & Bian, G.
Topological insulators, topological superconductors and Weyl fermion semimetals: discoveries, perspectives and outlooks.
Phys. Scr. 2015, 014001 (2015).
“.. recent experimental discoveries of non-quantum-Hall-like topological insulators, topological superconductors, Weyl semimetals and other topological states of matter also signal a clear departure from the quantum-Hall-effect-like transport paradigm that has dominated the field since the 1980s. It is these new forms of matter that enabled realizations of topological-Dirac, Weyl cones, helical-Cooper-pairs, Fermi-arc-quasiparticles and other emergent phenomena in fine-tuned photoemission (ARPES) experiments since ARPES experiments directly allow the study of bulk-boundary (topological) correspondence. In this proceeding we provide a brief overview of the key experiments and discuss our perspectives regarding the new research frontiers enabled by these experiments. Taken collectively, we argue in favor of the emergence of 'topological-condensed-matter-physics' in laboratory experiments...” (Non-QuantumHall-like Topological Matter)
Quantum-Hall-like Topological Matter are described by Chern (or “fractional Chern numbers”) with or without magnetic fields.
Our primary focus is on new states of matter (Non-Quantum Hall-like topological matter).
2004-2007: Discovery of Topo Surface States and Topo Insulators (2007)
https://www.pnas.org/doi/10.1073/pnas.1611504113
2007 KITP Proceedings: https://www.on.kitp.ucsb.edu/online/motterials07/hasan/
Discovery of New Phases of Matter : https://www.energy.gov/science/articles/energy-secretary-brouillette-announces-2020-ernest-orlando-lawrence-award-winners
Topo Insulator by itself is an incomplete story!! With the discovery of Topo Conductors (Semimetals), the basis set for the Topo Mat Universe led to completion…
Discovery of Topo Insulators led to Topo Semimetals (Weyl) -> defining "Topo Materials Universe"
https://www.nature.com/articles/s41578-021-00301-3
Discovery of New Phases of Topo Semimetals : https://www.energy.gov/science/articles/energy-secretary-brouillette-an…
Topo Materials Universe (Hasan group research) :
“Topological quantum matter is a new organizing principle for solids that has been experimentally established across multiple distinct phases in our work over the last two decades. This work demonstrated that electronic states in materials can be identified by topological invariants, giving rise to robust boundary states with unique spin texture and momentum structure protected against disorder. Using direct spectroscopic probes, these topological properties were visualized in real materials, providing unambiguous experimental confirmation of bulk–boundary correspondence and topological robustness.”
Discovery of New Phases of Matter: https://www.energy.gov/science/articles/energy-secretary-brouillette-announces-2020-ernest-orlando-lawrence-award-winners
Scientific American ("Topological Revolution"): https://www.scientificamerican.com/article/the-strange-topology-that-is-reshaping-physics/
News at Proc. of National Academy of Sciences: https://www.pnas.org/doi/10.1073/pnas.1611504113
American Academy: https://www.amacad.org/person/m-zahid-hasan
Hasan group's Theoretical Predictions of Topological Materials
A vast majority of our experimental works are based on our group’s own theoretical predictions of topological materials (see, for example) :
Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class (Bi2Se3 class) with spin-polarized single-Dirac-cone on the surface
https://arxiv.org/abs/0908.3513 (2009)
(Theoretical Prediction of Weyl semimetals in 2012)
"Topological Electronic Structure and WEYL Semimetal in the TlBiSe Class,"
Physical Review B 86, 115208 (2012).
"New Type of Weyl Semimetal with Quadratic Double Weyl Fermions,"
Proc. Natl. Acad. Sci. 113, 1180 (2015).
"A Weyl Fermion Semimetal with Surface Fermi Arcs in the Transition Metal Mono-pnictide TaAs Class,"
Nature Commun. 6:7373 (2015).
"Room-temperature Magnetic Weyl Semimetal and Nodal Line Semimetal States in Co2TiX (X=Si, Ge, or Sn),"
https://www.arxiv.org/pdf/1604.02124v1 (2016)
"Theoretical Prediction of Magnetic Weyl Semimetal States in the R-Al-X Family of Compounds" Physical Review B 97, 041104 (2018)
(Theoretical Prediction of ) Topological Hopf and Chain Link Semimetal States and Their Applications
Physical Review Letters 119, 156401 (2017)
(Theoretical Prediction of ) "Topological Quantum Properties of Weyl Chiral Crystals,"
Nature Materials 17, 978-985 (2018).
Topology : An organizing principle of quantum matter established through decisive experiments
"Topology is a fundamental organizing principle of matter, and our experiments directly visualize topological quantum states in real bulk materials.”
"Topology becomes real": Quantum mechanical topology measured through experiments of invariant imaging of many different classes of bulk materials reveals itself as a single conceptual organizing principle of quantum matter that our lab captures decisively via the measurements of bulk-boundary correspondence, experimentally establishing
“Topology as a fundamental principle (measurable bulk-boundary correspondence) behind the inner organization of quantum matter realized in bulk solids.” We have been developing methods and techniques to establish this 21st-century paradigm of physics in our Lab experimentally through a series of discoveries over the last two decades.
“Topological quantum matter is a new organizing principle for solids that has now been experimentally established across multiple distinct phases.”
Working Philosophy: “Experiment is the only means of knowledge at our disposal. Everything else is poetry, imagination” – Max Planck.
Contrast
String Theory Revolutions and QuantumTopological Invariants imaged in raw materials…
Prof. Hasan started his research training in QFT/TQFT/ST and later shifted his focus to innovative and decisive experimental physics that can pinpoint the rock-bottom reality of the natural world.
Dirac-Weyl topology: We applied Weyl theory to discover (both theoretically and experimentally) a variety of Weyl phenomena in topological materials (both theory and experiments) :
Field creation (invited reviews) : https://www.nature.com/articles/s41578-021-00301-3
https://www.annualreviews.org/content/journals/10.1146/annurev-conmatphys-031016-025225
The abstract concepts of Quantum Topology are shown through direct experiment to govern the electronic structure of many real quantum materials (bulk solids, both of insulating and of conductive).
Topology as an organizing principle of bulk solid
Topological quantum matter is a new organizing principle for solids that has been experimentally established across multiple distinct phases in our work over the last two decades. This work demonstrated that electronic states in materials can be identified by topological invariants, giving rise to robust boundary states with unique spin texture and momentum structure protected against disorder. Using direct spectroscopic probes, these topological properties were visualized in real materials, providing unambiguous experimental confirmation of bulk–boundary correspondence and topological robustness.
The first experimental realizations of three-dimensional topological insulators established topology as a measurable property of solids rather than a theoretical abstraction. Our subsequent discoveries showed that topology governs not only insulating phases but also gapless quantum matter, including Dirac and Weyl semimetals. The experimental identification of topological crystalline insulators revealed that crystal symmetries can protect new classes of topological states in a variety of materials. Together, these results demonstrated that topology provides a unifying framework connecting multiple, physically distinct symmetry-protected phases of quantum matter. These discoveries transformed topology from a mathematical abstract concept into an essential principle of modern condensed-matter physics in real bulk solids. The experimental signatures and materials platforms established here are now standard references in the field and are widely used across quantum materials research. Ongoing work continues to extend this framework, building on a foundation whose core principles are firmly established.
News at Proc. of National Academy of Sciences: https://www.pnas.org/doi/10.1073/pnas.1611504113
Scientific American: https://www.scientificamerican.com/article/the-strange-topology-that-is-reshaping-physics/
Opening new vistas: .. field-creation..
APS-Physics: "Topological Invariants via Spectroscopy (New Methods)
APS-Physics: "Topological Invariants via Spectroscopy (New Methods)
Topo Invariants precisely define a New Topo State of Matter which can be precisely measured via Spectroscopic measurements (no transport or quantum Hall transport is needed). This invited talk at APS-Physics elaborates this NEW method which enabled discovery of many novel topological states of matter…
Fermi-Arcs: Discovery of Fermi-Arc (Dirac-string) states in Topo Metals..
Fermi-Arcs: Discovery of Fermi-Arc (Dirac-string) states in Topo Metals..
Science (2014)
A New Paradigm : A Novel Method (Rev. of Mod. Phys. 82, 3045, 2010) for decisively measuring "Topological Invariants"
A New Paradigm : A Novel Method (Rev. of Mod. Phys. 82, 3045, 2010) for decisively measuring "Topological Invariants"
A New Paradigm : A Novel Method (see, invited review, RMP 82, 3045, 2010) for decisively measuring "topological invariants" which led to the creation of a new continent of research (the field of topological materials) with multiple groundbreaking discoveries, including topo. Dirac-Weyl fermions, Fermi arc and more..
https://journals.aps.org/rmp/abstract/10.1103/RevModPhys.82.3045
Theoretical Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class (Bi2Se3 class) with spin-polarized single-Dirac-cone on the surface
Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class (Bi2Se3 class) with spin-polarized single-Dirac-cone on the surface.
Intrinsic fully bulk INSULATING 3D-Topo-Insulators (Nature Physics 2014)
https://online.kitp.ucsb.edu/online/lsmatter_c15/hasan/oh/17.html
Theoretical Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class (Bi2Se3 class) with spin-polarized single-Dirac-cone on the surface
Topological kagome ...
Unexpected and unpredicted novel (many-body, correlated) quantum phenomena in Topological Kagome Magnets & Superconductors:
Unexpected and unpredicted novel (many-body, correlated) quantum phenomena in Topological Kagome Magnets & Superconductors:
Experiments started in 2017, completed in 2017, Nature’18, NaturePhys’19, PRL’19, PRL’20, NatureCom’20a, NatureCom’20b, NatureCom’20c, Nature’20, NatureMat’21, PRL’21, Science’19, Nature’19, Nature’22a, Nature’22b, PRL’22, NaturePhys’22, NatureCom’22, NatureCom’23a, NatureCom’23b, NaturePhys’23, NatureCom’24a, NatureCom’24b, NatureCom’24c, NatureMat’24
Novel quantum phenomena in Topological kagome magnets and superconductors (Nature 2022) :
Early works on 3D-TI ..
--
What is new?
What is New? Unlike string theory, topological physics in lower dimensional condensed matter systems is an experimental reality since the bulk-boundary correspondence can be probed experimentally in lower dimensions. Recent experimental discoveries of non-quantum-Hall-like topological insulators, topological superconductors, Weyl semimetals and other topological states of matter also signal a clear departure from the quantum-Hall-effect-like transport paradigm that has dominated the field since the 1980s. It is these new forms of matter that enabled realizations of topological-Dirac, Weyl cones, helical-Cooper-pairs, Fermi-arc-quasiparticles and other emergent phenomena in fine-tuned photoemission experiments since such experiments directly allow the study of band-inversion, spin-texture imaging, spin-momentum locking, bulk-boundary (topological) correspondence. Taken collectively, we argue in favor of the emergence of ‘topological-condensed-matter-physics’ in laboratory experiments for which a variety of theoretical concepts over the last 90 years (Dirac-Weyl topology, negative-Dirac-mass, Dirac-monopole-Berry charge, Aharonov-Bohm phase, C.Herring's exceptional points (modern Weyl node), Karplus-Luttinger theory (modern Berry curvature), 1979-SSH-chain, 1976-Jackiw-Rebbi and many foundational theories before and around 1970s – most topological theories are not new.. ) paved the way for modern experiments on Topological Materials ! Materials are not new either!
What is new? Advanced Spectroscopic experiments that enable precise determination of “Topological Invariants” (see, for a review, RMP 82, 3045 (2010)
Discovery of 2D & 3D Topological Magnets :
Theory and Experiments : “In this talk I present our* theoretical and experimental works on 2D and 3D topological magnets in novel Weyl and Dirac materials building up on earlier result but including recent results "A three-dimensional magnetic topological phase" Ilya Belopolski et.al., arXiv:1712.09992 (2017); "Topological quantum properties of chiral crystals" Guoqing Chang et.al., Nature Materials (2018); "Topological Hopf and Chain Link Semimetal States and Their Application to Co2MnGa" Physical Review Letters 119, 156401 (2017); "Magnetic Weyl fermion semimetals in the R-AlGe family of compounds" Physical Review B (2018) and Jiaxin Yin, Songtian Zhang et.al., "Giant and anisotropic many-body spin–orbit tunability in a strongly correlated kagome magnet" NATURE 562, 91–95 (2018). *Guoqing Chang, Bahadur Singh, Su-Yang Xu, Guang Bian, Shin-Ming Huang, Chuang-Han Hsu, Ilya Belopolski, Nasser Alidoust, Daniel S Sanchez, Hao Zheng, Hong Lu, Xiao Zhang, Yi Bian, Tay-Rong Chang, Horng-Tay Jeng, Arun Bansil, Han Hsu, Shuang Jia, Titus Neupert, Hsin Lin, Jia-Xin Yin, Songtian S. Zhang, Hang Li, Kun Jiang, Bingjing Zhang, Cheng Xiang, Hao Zheng, Tyler A. Cochran, Daniel Multer, Guang Bian, Kai Liu, Zhong-Yi Lu, Ziqiang Wang, Shuang Jia, Wenhong Wang, Biao Lian, Benjamin J. Wieder, Frank Schindler, Di Wu, Titus Neupert and Tay-Rong Chang” *DOE/BES (DE-FG-02-05ER46200) and GBMF4547 (EPIQS initiative)
Theories of Topo Matter (older than 1980s)
One of the earliest recognized forms of topological quantum phenomena is the Aharonov–Bohm effect (a fundamental example of how the global "topology" of space can affect quantum behavior). Flux quantization known from the 1950s or Karplus-Luttinger theory (long before the quantum Hall effect or its theory).
BCS theory --> Tunneling expts (Giaever et.al., confirms BCS theory)
Beautiful tunneling experiments validated BCS theory, see, Ivar Giaever's Nobel-winning papers in PRL experimentally confirming the Bardeen-Cooper-Schrieffer (BCS) theory. Josephson's theory was confirmed in a series of tunneling experiments.
Similarly, the Bose-Einstein Condensation theory was experimentally confirmed in cold-atom spectroscopic experiments (confirming BEC theory in experiments via spectroscopic methods, Nobel 2001).
“Experiment is the only means of knowledge at our disposal. Everything else is poetry, imagination” – Max Planck.
Dirac theory --> Graphene expts (Novoselov et.al., confirms Dirac/Wallace theory)
Wallace applied Dirac's theory to graphene. Graphene experiments validated the Dirac theory of Wallace.
Weyl theory --> Weyl phenomena in topological materials
We applied Weyl theory to discover (both theoretically and experimentally) a variety of Weyl phenomena in topological quantum materials (both theory and experiments) :
Field creation (invited reviews) : https://www.nature.com/articles/s41578-021-00301-3 and https://www.annualreviews.org/content/journals/10.1146/annurev-conmatphys-031016-025225 and https://www.nature.com/articles/nmat4787
Discovery of Topological Semimetals : https://www.annualreviews.org/content/journals/10.1146/annurev-conmatphys-031016-025225
Unlike graphene, topological Weyl phenomena and their topological generalizations have been discovered and demonstrated in many classes of quantum materials.
Hasan Lab focus:
Abstract-Math → Tangible Materials in Lab (Quantum-Topology hand-held reality in Lab)
On the experimental side,
the Hasan lab has been focused on establishing direct experimental visualization of topological invariants via bulk-boundary contrast measurements, transforming topology
from “abstract mathematics” into
“a tangible physical reality”
of directly measurable and imagable materials in lab.
A few of our results, including topological insulators and Weyl, Dirac topological semimetals, Nodal-line topological metals, are now included in many standard textbooks of condensed matter physics [see, for example, “Modern Condensed Matter Physics” by K. Yang and Steven Girvin (Yale University) ] (Cambridge Univ. Press).
Our systematic experiments established New States of Matter as a physical reality (unlike the string theory-type paradigms of abstract concepts).
News: https://www.energy.gov/science/articles/energy-secretary-brouillette-an…
Experimental Foundations of Modern "Topo Quantum Matter"
“Topological quantum matter is a new organizing principle for bulk solids that has now been experimentally established across multiple distinct phases.” (Topo Insulators, Topo Magnets, Weyl-Dirac semimetals, Nodal-loop magnets, Fermi-arc metals and more)
Recent results ...
Unexpected and unpredicted novel (many-body, correlated) quantum phenomena in Topological Kagome Magnets & Superconductors:
Unexpected and unpredicted novel (many-body, correlated) quantum phenomena in Topological Kagome Magnets & Superconductors:
Experiments started in 2017, completed in 2017, Nature’18, NaturePhys’19, PRL’19, PRL’20, NatureCom’20a, NatureCom’20b, NatureCom’20c, Nature’20, NatureMat’21, PRL’21, Science’19, Nature’19, Nature’22a, Nature’22b, PRL’22, NaturePhys’22, NatureCom’22, NatureCom’23a, NatureCom’23b, NaturePhys’23, NatureCom’24a, NatureCom’24b, NatureCom’24c, NatureMat’24
Novel quantum phenomena in Topological kagome magnets and superconductors : https://www.nature.com/articles/s41586-022-05516-0
Theoretical Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class (Bi2Se3 class) with spin-polarized single-Dirac-cone on the surface
Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class (Bi2Se3 class) with spin-polarized single-Dirac-cone on the surface
Theoretical Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class (Bi2Se3 class) with spin-polarized single-Dirac-cone on the surface
Single-Dirac-cone topology ..
Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class (Bi2Se3 class) with spin-polarized single-Dirac-cone on the surface
Theoretical Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class (Bi2Se3 class) with spin-polarized single-Dirac-cone on the surface
https://arxiv.org/abs/0908.3513
Intrinsic fully bulk INSULATING 3D-Topo-Insulators (Nature Physics 2014)
https://online.kitp.ucsb.edu/online/lsmatter_c15/hasan/oh/17.html
https://arxiv.org/abs/0908.3513 (2009) [Submitted to Nature Phys in 2008 ]
--
--
Weyl topology
Weyl topology
What is New?
What is New? Unlike string theory, topological physics in lower dimensional condensed matter systems is an experimental reality since the bulk-boundary correspondence can be probed experimentally in lower dimensions. Recent experimental discoveries of non-quantum-Hall-like topological insulators, topological superconductors, Weyl semimetals and other topological states of matter also signal a clear departure from the quantum-Hall-effect-like transport paradigm that has dominated the field since the 1980s. It is these new forms of matter that enabled realizations of topological-Dirac, Weyl cones, helical-Cooper-pairs, Fermi-arc-quasiparticles and other emergent phenomena in fine-tuned photoemission experiments since such experiments directly allow the study of band-inversion, spin-texture imaging, spin-momentum locking, bulk-boundary (topological) correspondence. Taken collectively, we argue in favor of the emergence of ‘topological-condensed-matter-physics’ in laboratory experiments for which a variety of theoretical concepts over the last 90 years (Dirac-Weyl topology, negative-Dirac-mass, Dirac-monopole-Berry charge, Aharonov-Bohm phase, C.Herring's exceptional points (modern Weyl node), Karplus-Luttinger theory (modern Berry curvature), 1979-SSH-chain, 1976-Jackiw-Rebbi and many foundational theories before and around 1970s – most topological theories are not new.. ) paved the way for modern experiments on Topological Materials ! Materials are not new either!
What is new? Advanced Spectroscopic experiments that enable precise determination of “Topological Invariants” (see, for a review, RMP 82, 3045 (2010)
Weyl topology
A Paradigm Shift ...
A Novel Method (see, invited Rev. of Mod. Phys. 82, 3045, 2010) for decisively measuring "topological invariants" led to the creation of a new continent of research with multiple groundbreaking discoveries including topo. Dirac-Weyl fermions and more..
2007- Experimental discovery of Topological Insulator via the measurements of Topological Invariants. Transport measurements cannot directly measure the invariants; therefore, this spectroscopic work constitutes the first proof and direct visualization of the new topology. Following this new experimental methodology, a new set of seminal discoveries followed ..
"A New Continent" (2007-) : New Phases of Matter required a new experimental method ..
In this lab, Hasan group uses advanced spectroscopy, microscopy (STM/STS), and transport to explore quantum materials physics and the new frontiers.
Non-Quantum-Hall-like topological physics (New Phases of Matter) : While transport techniques proved to be quite ambiguous in isolating surface-bulk isolation for decisively discovering topology and the associated topological invariants (new invariants beyond Chern number), during 2004-2007, the Hasan team demonstrated novel methods to measure topological matter without measuring transport [ 2007 KITP Proceedings https://www.on.kitp.ucsb.edu/online/motterials07/hasan/ ] . Previous methods were based on Hall transport, a century-old method of measuring topology, which is limited to the exploration of 2D topological physics, including all forms of quantum Hall-like phenomena (and their many descendants described by the Chern number and related physics). It is our new method (spectroscopy-based schemes) of measuring “topological invariants” directly, precisely, and unambiguously that has led to a new experimental revolution in the field of topological matter discovery, with a focus on Non-Quantum-Hall-like (the New Continental Paradigm) topological physics. … including many unpredicted and unexpected novel quantum phenomena discovered experimentally, not envisioned even in theory in these materials… It is this new paradigm of experimental topological physics exploration that led to new inventions, breakthroughs, and patents (see reviews and links below) :
"A New Continent" opened up for quantum research (not just some effect or a material)
Experimental Foundations of Modern “Topological Quantum Matter” (Field-defining breakthroughs are described in the following invited reviews)
Hasan et.al., Phys. Scr. 2015, 014001 (2015).
Hasan et.al, "Topological Insulators, Topological Dirac Semimetals, Topological Crystalline Insulators, and Topological Kondo Insulators," in Topological Insulators: Fundamentals and Perspectives, edited by F. Ortmann, S. Roche, and S. Valenzuela (John Wiley & Sons, 2015).
Hasan et.al., Ann. Reviews Cond.Mat.Phys. 8, 289 (2017).
Hasan et.al., Nature Reviews Materials 6, 784 (2021)
Hasan et.al., Reviews of Modern Physics 82, 3045 (2010)
Max Planck and Quantum Pioneers et.al., “Experiment is the only means of knowledge at our disposal. Everything else is poetry, imagination (not guaranteed by nature)” – Max Planck.
New Phases of Matter (beyond Quantum Hall-like physics) : https://www.energy.gov/science/articles/energy-secretary-brouillette-an…
“A new continent with a distinct culture with new terms and linguistic expressions” (2007-)
Once you discover a new contitent you need new terms to describe new things you encounter : Historically, during 2007-08, upon entering a new contitent, Hasan's lab coined the terms “Topological Helical Spin-Textures”, “Topological Quantum Matter”, “Helical Dirac Fermion”, and “Topological Dirac Insulator” in an effort to describe to the world physically measurable topological quantum properties based on the spectroscopic methods (not transport) not familiar from the old quantum-Hall-effect paradigm. These terms were not introduced in the early theory literature (neither by Kane nor Haldane papers). We coined these terms primarily to describe experimentally measurable topological quantities that naturally arise in our experimental techniques, which are beyond the quantum Hall-type transport measurements. Theorists did not invent these terms in their papers, nor did they describe how to measure most of these quantities. We showed that many of these “topological invariant”-related quantities are spectroscopically measurable. Many of these are our inventions, hence our terminology that researchers now use worldwide. It is not a single discovery but “a new continent with a distinct culture” that we had to figure out how to describe succinctly.
News in Proc. of National Academy of Sciences: https://www.pnas.org/doi/full/10.1073/pnas.1611504113
Broader Impact (Field-Creation):
Textbook inclusion:
A few of our results, including topological insulators and Weyl, Dirac topological semimetals, Nodal-line topological metals, are now included in many standard textbooks of condensed matter physics [see, for example, “Modern Condensed Matter Physics” by K. Yang and Steven Girvin (Yale University) ] (Cambridge Univ. Press)
Multiple breakthrough discoveries in our labs have been featured in Physics Today, Physics World, Scientific American, Nature News, Science News, Discover magazine, New Scientist, and similar media, including Physics Today’s “Search & Discovery News” multiple times over the last two decades.
Citation tracks:
Many researchers are now exploring this new continent that we stumbled upon in 2007: 100,000+ peer citations (~ 10,000/year impact growth rate) – We created a paradigm-shifting new platform to discover topological materials (not a single discovery but an entire experimental field of physics), which are now used by others worldwide to advance the field to new frontiers further and make new discoveries beyond the old quantum Hall-like transport methods. This is evident from all citation tracking algorithms.
A vast majority of our topological materials discoveries were based on our own theoretical predictions, as we are funded by multiple grant agencies for conducting theoretical research (see details: https://www.amacad.org/person/m-zahid-hasan). Hasan was originally trained as a theorist working at the Weinberg Theory Center in the 1990s). He continues to receive funding for his theoretical research in advanced topological materials. Additionally, the Hasan group uses spectroscopy, microscopy, and transport to explore novel quantum materials.
Field-Creation Review:
Based on research work at Hasan Lab spanning the experimental period 2004-10, a methodological and conceptual summary is given in the invited review article, Hasan & Kane RMP 82, 3045 (2010). This review has been cited about 25,000+ times by the community of researchers actively pursuing this new field of research.
Field-Creation & Successive Generative Legacy:
Quantum matter research is amplified and continued.. Previous PhD graduate students from Hasan group at Princeton have gone on to win Pappalardo fellowship (MIT), Urbanic fellowship (Stanford), Simons fellowship (Columbia), Miller Fellowship (UC Berkeley), GLAM fellowship (Stanford), Postdoc at Stanford, MIT, Princeton, Columbia and many other top fellowships or postdoctoral positions at national labs (Berkeley Lab, Argonne, PSI-Zurich, SLAC/Stanford etc.) and industrial internships including at Google (QuantumAI group), IBM, QuEra, Rigetti quantum computing. Group Alum in Academia ..A number of Hasan group PhD students have also gone on to win faculty positions at top research institutions such as Caltech, Harvard University, NYU, University of California, Univ of Florida, UCLA, Univ of Florida, NUS, Univ of Minnesota and many others around the world including the national labs such as Berkeley Lab, SLAC/Stanford, Argonne, PSI-Switzerland etc.
This resulted in continued world-class research on topological quantum matter, leading to the birth of a new field of physics with explosive activities that continues for more than two decades…
New Frontiers:
We are further expanding and deepening the modern experimental foundations of “Topological Quantum Matter” as a major pillar of condensed matter physics in the 21st century to ever new frontiers .... (stay tuned!)
“Experiment is the only means of knowledge at our disposal. Everything else is poetry, imagination” – Max Planck.
Non-QuantumHall-like New Topological Phases of Matter
“.. recent experimental discoveries of non-quantum-Hall-like topological insulators, topological superconductors, Weyl-Dirac topological semimetals and other topological states of matter also signal a clear departure from the quantum-Hall-effect-like transport paradigm that has dominated the field since the 1980s. It is these new forms of matter that enabled realizations of topological-Dirac, Weyl cones, helical-Cooper-pairs, Fermi-arc-quasiparticles and other emergent phenomena in fine-tuned photoemission (ARPES) experiments since ARPES experiments directly allow the study of bulk-boundary (topological) correspondence. In this proceeding we provide a brief overview of the key experiments and discuss our perspectives regarding the new research frontiers enabled by these experiments. Taken collectively, we argue in favor of the emergence of 'topological-condensed-matter-physics' in laboratory experiments...” (Non-QuantumHall-like Topological Matter). Experimental Foundation of Modern Topological Quantum Matter:
Hasan et.al., Phys. Scr. 2015, 014001 (2015).
Textbook inclusion
Textbook inclusion of Experimental Results from our Lab : A few of our results, including Topological Insulators and Weyl-Dirac Semimetals, are now included in many standard textbooks of condensed matter physics [see, for example, “Modern Condensed Matter Physics” by K. Yang and Steven Girvin (Yale University) ]
Topological Invariants measured via Spectroscopy ..
Intrinsic fully bulk INSULATING 3D-Topo-Insulators (Nature Physics 2014)
Intrinsic fully bulk INSULATING 3D-Topo-Insulators (Nature Physics 2014)
https://online.kitp.ucsb.edu/online/lsmatter_c15/hasan/oh/17.html
KITP Lecture link .. https://www.on.kitp.ucsb.edu/online/lowdim09/hasan/oh/01.html
KITP Lecture link ..
https://www.on.kitp.ucsb.edu/online/lowdim09/hasan/oh/01.html
Fermi-Arcs: Discovery of Fermi-Arc (Dirac-string) states in Topo Metals..
Fermi-Arcs: Discovery of Fermi-Arc (Dirac-string) states in Topo Metals..
Science (2014)
A New Paradigm : A Novel Method (Rev. of Mod. Phys. 82, 3045, 2010) for decisively measuring "Topological Invariants"
A New Paradigm : A Novel Method (Rev. of Mod. Phys. 82, 3045, 2010) for decisively measuring "Topological Invariants"
A New Paradigm : A Novel Method (see, invited review, RMP 82, 3045, 2010) for decisively measuring "topological invariants" which led to the creation of a new continent of research (the field of topological materials) with multiple groundbreaking discoveries, including topo. Dirac-Weyl fermions, Fermi arc and more..
https://journals.aps.org/rmp/abstract/10.1103/RevModPhys.82.3045
Why Weyl ...
--
New Methods ...
Early works on 3D-TI ..
Measuring Chern no. via ARPES
Top-10
KITP lecture ...
STM/STS
Topology ..
Weyl
Physics World 2011
Quantum Matter ..
--
Unexpected and unpredicted novel (many-body, correlated) quantum phenomena in Topological Kagome Magnets & Superconductors:
Unexpected and unpredicted novel (many-body, correlated) quantum phenomena in Topological Kagome Magnets & Superconductors:
Experiments started in 2017, completed in 2017, Nature’18, NaturePhys’19, PRL’19, PRL’20, NatureCom’20a, NatureCom’20b, NatureCom’20c, Nature’20, NatureMat’21, PRL’21, Science’19, Nature’19, Nature’22a, Nature’22b, PRL’22, NaturePhys’22, NatureCom’22, NatureCom’23a, NatureCom’23b, NaturePhys’23, NatureCom’24a, NatureCom’24b, NatureCom’24c, NatureMat’24
Novel quantum phenomena in Topological kagome magnets and superconductors (Nature 2022) :
--
Chern topological magents ..
Why Weyl?
Weyl topology
Weyl topology
--
Why Weyl ?
Recent research ..
--
Spin-resolved ARPES as a probe of topological quantum spin Hall effect and Berry's phase
Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class (Bi2Se3 class) with spin-polarized single-Dirac-cone on the surface
Theoretical Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class (Bi2Se3 class) with spin-polarized single-Dirac-cone on the surface
https://arxiv.org/abs/0908.3513
Intrinsic fully bulk INSULATING 3D-Topo-Insulators (Nature Physics 2014)
https://online.kitp.ucsb.edu/online/lsmatter_c15/hasan/oh/17.html
https://arxiv.org/abs/0908.3513 (2009) [Submitted to Nature Phys in 2008 ]
--
--
--
What is New?
What is New? Unlike string theory, topological physics in lower dimensional condensed matter systems is an experimental reality since the bulk-boundary correspondence can be probed experimentally in lower dimensions. Recent experimental discoveries of non-quantum-Hall-like topological insulators, topological superconductors, Weyl semimetals and other topological states of matter also signal a clear departure from the quantum-Hall-effect-like transport paradigm that has dominated the field since the 1980s. It is these new forms of matter that enabled realizations of topological-Dirac, Weyl cones, helical-Cooper-pairs, Fermi-arc-quasiparticles and other emergent phenomena in fine-tuned photoemission experiments since such experiments directly allow the study of band-inversion, spin-texture imaging, spin-momentum locking, bulk-boundary (topological) correspondence. Taken collectively, we argue in favor of the emergence of ‘topological-condensed-matter-physics’ in laboratory experiments for which a variety of theoretical concepts over the last 90 years (Dirac-Weyl topology, negative-Dirac-mass, Dirac-monopole-Berry charge, Aharonov-Bohm phase, C.Herring's exceptional points (modern Weyl node), Karplus-Luttinger theory (modern Berry curvature), 1979-SSH-chain, 1976-Jackiw-Rebbi and many foundational theories before and around 1970s – most topological theories are not new.. ) paved the way for modern experiments on Topological Materials ! Materials are not new either!
What is new? Advanced Spectroscopic experiments that enable precise determination of “Topological Invariants” (see, for a review, RMP 82, 3045 (2010)
Discovery of 2D & 3D Topological Magnets :
Theory and Experiments : “In this talk I present our* theoretical and experimental works on 2D and 3D topological magnets in novel Weyl and Dirac materials building up on earlier result but including recent results "A three-dimensional magnetic topological phase" Ilya Belopolski et.al., arXiv:1712.09992 (2017); "Topological quantum properties of chiral crystals" Guoqing Chang et.al., Nature Materials (2018); "Topological Hopf and Chain Link Semimetal States and Their Application to Co2MnGa" Physical Review Letters 119, 156401 (2017); "Magnetic Weyl fermion semimetals in the R-AlGe family of compounds" Physical Review B (2018) and Jiaxin Yin, Songtian Zhang et.al., "Giant and anisotropic many-body spin–orbit tunability in a strongly correlated kagome magnet" NATURE 562, 91–95 (2018). *Guoqing Chang, Bahadur Singh, Su-Yang Xu, Guang Bian, Shin-Ming Huang, Chuang-Han Hsu, Ilya Belopolski, Nasser Alidoust, Daniel S Sanchez, Hao Zheng, Hong Lu, Xiao Zhang, Yi Bian, Tay-Rong Chang, Horng-Tay Jeng, Arun Bansil, Han Hsu, Shuang Jia, Titus Neupert, Hsin Lin, Jia-Xin Yin, Songtian S. Zhang, Hang Li, Kun Jiang, Bingjing Zhang, Cheng Xiang, Hao Zheng, Tyler A. Cochran, Daniel Multer, Guang Bian, Kai Liu, Zhong-Yi Lu, Ziqiang Wang, Shuang Jia, Wenhong Wang, Biao Lian, Benjamin J. Wieder, Frank Schindler, Di Wu, Titus Neupert and Tay-Rong Chang” *DOE/BES (DE-FG-02-05ER46200) and GBMF4547 (EPIQS initiative)
Quantum Frontiers ..
Hasan Lab research is focused on exploring novel physics of quantum-many-body emergence, correlated electron physics, Bose condensates, quantum coherence, and topological (weakly or strongly interacting, quantum entangled, topology and entanglement) emergence by combining novel spectroscopy, microscopy and transport methods. Deeper understanding and systematic control of quantum phenomena not only advance our knowledge of the laws of nature but also lay the foundation for future technologies.
We develop tools capable of providing deep insights into the correlated motion of electrons in strongly correlated quantum systems and topological materials featuring emergent phenomena.
We also develop tools and methods to understand, theoretically predict and control emergent phenomena in materials https://www.moore.org/investigator-detail?investigatorId=hasan
Discovering Novel Topological Quantum Matter & Unpredicted/Unexpected novel quantum phenomena ..
“Experiment is the only means of knowledge at our disposal. Everything else is poetry, imagination (not guaranteed by nature)” – Max Planck.
Over the last two decades our group has been active in generating novel ideas, methodolgies and instrumentations to create next-generation tools for quantum materials research and discovery.
We utilize and develop (or further develop) advanced state-of-the-art spectroscopic and microscopic and transport techniques and their various futuristic incarnations to explore novel quantum phenomena enabling major discoveries (see publications and citation impact), including low temperature ARPES, spin-ARPES, STM, STS and ultrafast optical & THz, MBE-STM, spin-STS, SC-STS techniques to explore charge, spin, orbital and lattice degrees of freedom in novel quantum topological and strongly correlated matter (quantum many-body physics).
A vast majority of our experimental discoveries are based on our group's theoretical predictions of topological materials, funded by several grant agencies.
Theory:
Theoretical predictions (discovery) of novel topological materials in Hasan group:
https://www.moore.org/investigator-detail?investigatorId=hasan
https://www.amacad.org/person/m-zahid-hasan
https://www.moore.org/investigator-detail?investigatorId=hasan
Novel Instrumentation:
We are currently developing new experimental methods. Please visit the lab to learn more about experimental details and instrumental capabilities being developed.
Theory & Experiments:
Theoretical Prediction and experimental discovery of novel topological materials and exotic quantum phenomena:
Research Description: https://www.amacad.org/person/m-zahid-hasan
News at PNAS: https://www.pnas.org/doi/10.1073/pnas.1611504113
Physics Today’s “Search & Discovery News”:
Novel and advanced state-of-the-art instrumentation (technique development) :
Princeton Lab: https://zahidhasangroup.scholar.princeton.edu/research-highlights
Unexpected and unpredicted novel (many-body, correlated) quantum phenomena ..
Unexpected and unpredicted novel (many-body, correlated) quantum phenomena in Topological Kagome Magnets & Superconductors:
Experiments started in 2017, completed in 2017, Nature’18, NaturePhys’19, PRL’19, PRL’20, NatureCom’20a, NatureCom’20b, NatureCom’20c, Nature’20, NatureMat’21, PRL’21, Science’19, Nature’19, Nature’22a, Nature’22b, PRL’22, NaturePhys’22, NatureCom’22, NatureCom’23a, NatureCom’23b, NaturePhys’23, NatureCom’24a, NatureCom’24b, NatureCom’24c, NatureMat’24, NaturePhysics'25
Discovery of novel quantum phenomena in Topological kagome magnets and superconductors : https://www.nature.com/articles/s41586-022-05516-0
Non-QuantumHall-like Topological Matter
Hasan, M. Z., Xu, S.-Y. & Bian, G.
Phys. Scr. 2015, 014001 (2015).
“.. recent experimental discoveries of non-quantum-Hall-like topological insulators, topological superconductors, Weyl semimetals and other topological states of matter also signal a clear departure from the quantum-Hall-effect-like transport paradigm that has dominated the field since the 1980s. It is these new forms of matter that enabled realizations of topological-Dirac, Weyl cones, helical-Cooper-pairs, Fermi-arc-quasiparticles and other emergent phenomena in fine-tuned photoemission (ARPES) experiments since ARPES experiments directly allow the study of bulk-boundary (topological) correspondence. In this proceeding we provide a brief overview of the key experiments and discuss our perspectives regarding the new research frontiers enabled by these experiments. Taken collectively, we argue in favor of the emergence of 'topological-condensed-matter-physics' in laboratory experiments...” (Non-QuantumHall-like Topological Matter)
A New Paradigm : A Novel Method (Rev. of Mod. Phys. 82, 3045, 2010) for decisively measuring "Topological Invariants"
A New Paradigm : A Novel Method (Rev. of Mod. Phys. 82, 3045, 2010) for decisively measuring "Topological Invariants"
A New Paradigm : A Novel Method (see, invited review, RMP 82, 3045, 2010) for decisively measuring "topological invariants" which led to the creation of a new continent of research (the field of topological materials) with multiple groundbreaking discoveries, including topo. Dirac-Weyl fermions, Fermi arc and more..
https://journals.aps.org/rmp/abstract/10.1103/RevModPhys.82.3045
Unexpected and unpredicted novel (many-body, correlated) quantum phenomena in Topological Kagome Magnets & Superconductors:
Unexpected and unpredicted novel (many-body, correlated) quantum phenomena in Topological Kagome Magnets & Superconductors:
Experiments started in 2017, completed in 2017, Nature’18, NaturePhys’19, PRL’19, PRL’20, NatureCom’20a, NatureCom’20b, NatureCom’20c, Nature’20, NatureMat’21, PRL’21, Science’19, Nature’19, Nature’22a, Nature’22b, PRL’22, NaturePhys’22, NatureCom’22, NatureCom’23a, NatureCom’23b, NaturePhys’23, NatureCom’24a, NatureCom’24b, NatureCom’24c, NatureMat’24
Novel quantum phenomena in Topological kagome magnets and superconductors (Nature 2022) :
Hasan lab is focused (funded to work) on the conceptualization, design, search and discover, theoretical prediction, experimental discovery and development of new physics of quantum matter. The Lab research is focused on exploring novel physics of quantum-many-body emergence, condensates, quantum coherence, and topological (weakly or strongly interacting, entangled) emergence by combining novel spectroscopy, microscopy and transport methods including ARPES, STM/STS, Ultrafast/THz Optics (on topological and correlated quantum materials).
Lab History (Research Summary)
The terms "Topological Quantum Matter" & "Topological Dirac Insulator" were coined in 2007
https://phy.princeton.edu/people/m-zahid-hasan
Substantially responsible (90,000+ citations) for opening 5 major research fronts in modern condensed matter physics over last two decades:
Topological Surface States and Topo Insulators: Discovery & Fundamental Properties
Experiments started in 2004, completed in 2007, paper submitted in 2007 KITP proceeding: https://www.on.kitp.ucsb.edu/online/motterials07/hasan/ KITP’2007, Nature’08 (submitted in 2007), Nature’09a, Nature’09b, Science’09, NaturePhys’09, PRL’09, PRL’10, NatureMat’10, NaturePhys’11a, NaturePhysics’11b, NaturePhys’12, Science’13, NatureCom’13, NaturePhys’14a, NaturePhys’14b, NatureCom’14, PRL’15, ScienceAdv’17, NatureMat’22, NaturePhys 20, 1253 (2024). NaturePhys 20, 776 (2024), Nature 628, 527 (2024).
News on the discovery of topological surface states: https://newscenter.lbl.gov/2017/04/14/how-x-rays-pushed-topological-mat…
Topological Magnets including Chern magnets: Discovery & Fundamental Properties
Experiments started in 2008, completed in 2011, arXiv(2008), NatPhys’11, NaturePhys’12 (Chern gap in 2012), Nature’18, Science’19, Nature’20, PRL’21, Nature’22a, Nature’22b, NaturePhys’23, NatureCom’24
APS invited talk on the discovery : https://absuploads.aps.org/presentation.cfm?pid=14503
Topological Weyl/Dirac semimetals: Discovery & Fundamental Properties
Experiments started in 2011, completed in 2014. APS invited talk on the Discovery: https://absuploads.aps.org/presentation.cfm?pid=14503 Science’11, PRB’12, NatureCom’15 (submitted in 2014), Science’15a (submitted in 2014), Science’15b, NaturePhys’15, PRL’16, NatureCom’16a, NatureCom’16b, PRL’17a, PRL’17b, PRL’17c, NaturePhys’17, NatureCom’17, NatureMat’18, Science’19, Nature’18, Nature’19, PRl’20, NatureCom’20, PRL’23a, PRL’23b, NatureCom’23, NaturePhys’23, Nature’24
Topological Phase Transitions in 3D
Experiments started in 2009, completed in 2010, Science’11, PRL’12, NatureCom’12, NaturePhys’12, NatureCom’15, NaturePhys’15, Nature’18, Science’19, Nature’19, PRL’19
Topological Phase Transition & Texture Inversion: https://www.science.org/doi/10.1126/science.1201607#:~:text=In%20the%20….
Unexpected and unpredicted novel (many-body, correlated) quantum phenomena in Topological Kagome Magnets & Superconductors:
Experiments started in 2017, completed in 2017, Nature’18, NaturePhys’19, PRL’19, PRL’20, NatureCom’20a, NatureCom’20b, NatureCom’20c, Nature’20, NatureMat’21, PRL’21, Science’19, Nature’19, Nature’22a, Nature’22b, PRL’22, NaturePhys’22, NatureCom’22, NatureCom’23a, NatureCom’23b, NaturePhys’23, NatureCom’24a, NatureCom’24b, NatureCom’24c, NatureMat’24
Discovery of novel quantum phenomena in Topological kagome magnets and superconductors : https://www.nature.com/articles/s41586-022-05516-0
Key Inventions & patents related to the research fronts :
First example of Weyl semimetals and the methods for its discovery US Patent#10214797 “Method for production and identification of Weyl semimetal” (2016)
First example of room-temperature topological quantum edge state
“Identification Procedure of Room-Temp. Quantum Spin Hall Topological Edge State”
PATENT FILING Ref#: 24-4088-1 (2024)
Fabrication of Quantum Devices using intrinsic insulating topological materials
“Quantum device using insulating topo. material” PATENT FILING Ref#: 24-4093-1 (2024)
Research works have been featured in Physics Today, Physics World, Scientific American, Nature News, Science News, Discover magazine, New Scientist and similar media including Physics Today’s “Search & Discovery News” multiple times over the last two decades. According to U.S. Department of Energy, these “experiments led to seminal discoveries of new phases of matter and new fermionic quasiparticles.” The research work “opened new areas in condensed matter physics and holds promise for future transformative applications in materials sciences” Source: https://www.energy.gov/science/articles/energy-secretary-brouillette-announces-2020-ernest-orlando-lawrence-award-winners
According to the American Academy, these “results have extended our old textbook level understanding of quantum matter and are now being featured in many standard textbooks of condensed matter physics used in universities world-wide.”
Strongly correlated electron physics:
Quantum many-body physics in doped Mott insulators, Charge-order and Superconductivity competition, Nematic order & fluctuations etc. (Hasan lab research)
Hasan et.al., Phys. Rev. Lett. 92, 246402 (2004); Phys. Rev. Lett. 96, 046407 (2006); Phys. Rev. Lett. 97, 186405 (2006); Phys. Rev. Lett. 96, 216405 (2006). Phys. Rev. Lett. 98, 117007 (2007) and Phys. Rev. Lett. 99, 167002 (2007). Phys. Rev. B 78, 184508 (2008); Phys. Rev. Lett. 103, 037002 (2009). Nature’18, NaturePhys’19, PRL’19, PRL’20, NatureCom’20a, NatureCom’20b, NatureCom’20c, Nature’20, NatureMat’21, PRL’21, Science’19, Nature’19, Nature’22a, Nature’22b, PRL’22, NaturePhys’22, NatureCom’22, NatureCom’23a, NatureCom’23b, NaturePhys’23, NatureCom’24a, NatureCom’24b, NatureCom’24c, NatureMat’24
Experimental Inventions & Breakthroughs ..
# Developed methods for determining Z2 topological invariants and Mirror Chern numbers from spin-ARPES experiments alone without referring to theory (Nature 2009, Science 2009, Science 2011). These detailed methods were used to demonstrate that the 3D Topological Insulators are a new and distinct state of matter, which cannot be reduced to multiple copies of IQH, and there is no spin Hall effect in 3D. The 3D state is thus an example of non-quantum-Hall-like topological matter and the first realization of topologically ordered bulk solid in nature (Physics World 2011, Physics Today 2010).
# Demonstrated that electrons on the surface of some spin-orbit materials form a topologically-ordered two dimensional gas with a non-trivial Berry's phase (arXiv:0812.2078 (2008), Nature 2009)
# Developed methods for the demonstration of spin-momentum locking without utilizing any transport method (Nature 2009, Science 2009, Science 2011)
# Developed methods for the determination of Chern invariant and Chern gap from spin-ARPES experiments (Nature Physics 2012)
# Developed methods and algorithms for the identification of chiral fermions (Weyl and other chiral fermions) from spectroscopic experiments without replying on band-structure measurements (Science 2015a, Nature Physics 2015, Science 2015b)
# Developed methods and algorithms for the identification of Fermi arc fermions "Criteria for Directly Detecting (Proving) Topological Fermi Arcs" (Phys. Rev. Lett. 116, 066802 (2016))
# Demonstrated methods and algorithms for “Momentum-space imaging of Cooper pairing in a half-Dirac-gas Superconductor (based on a topological insulator)” (Nature Physics 10, 943 (2014))
# Demonstrated Adiabatic continuation approach to theoretically predict topo. materials Working with Hsin Lin demonstrated that first-principles-based adiabatic continuation approach is a powerful and efficient tool for constructing topological phase diagrams and locating non-trivial topological insulator materials. Applied to real materials, results demonstrated the efficacy of adiabatic continuation for exploring topologically nontrivial alloying systems and for identifying new topological insulators even when the underlying lattice does not possess inversion symmetry, and the approaches based on parity analysis of Fu-Kane methods are not viable. (Nature Materials 9, 546 (2010); Phys. Rev. B 87, 121202(R) (2013).)
# Discovery (Theoretical Prediction & Experimental Demonstration) of Weyl semimetals -- Weyl fermion and topological Fermi arcs in spin-orbit materials (Science 349, 613 (2015); Science 347, 294 (2015). Nature Phys 11, 748 (2015))
# Developed and demonstrated a novel artificial condensed matter lattice and a new platform for one-dim. topological phases (Science Advances 3, e1501692 (2017))
# Demonstrated quantum transport in bulk insulating topological insulators and Quantum transport response of topological hinge modes in a topological insulator (Nature Physics 20, 776–782 (2024) and Nature Physics 10, 956-963 (2014))
# First Observation of Chern gap in 2012 Hedgehog spin texture and Berry's phase tuning in a magnetic topological insulator (Nature Physics 8, 616 (2012))
# First example of Weyl semimetals and the methods for its discovery US Patent#10214797 “Method for production and identification of Weyl semimetal” (2016)
# Discovered and demonstrated Topological nodal-line (continuous Dirac/Weyl) semimetals (2015-2016) Led in the theoretical prediction and experimental discovery of topological nodal-line semimetals (Nature Commun (2016), arXiv 2015) and elucidated their nontrivial topological electronic structure including Dirac loop Fermi surfaces known as nodal rings (demonstrated in PbTaSe2 and TlTaSe2) (Nature Commun. 7:10556 (2016); Physical Review B (2016))
# Demonstrated Giant and anisotropic many-body spin–orbit tunability in a correlated topo. kagome magnet (NATURE 562, 91–95 (2018))
# Demonstrated Quantum-limit Chern topological magnet (NATURE 583, 533 (2020))
# Demonstrated Magnetic-field control of topological electronic response near room temperature in correlated Kagome magnets (Physical Review Letters 123, 196604 (2019))
# Demonstrated Many-body Resonance in a Correlated Topological Kagome Antiferromagnet (Phys. Rev. Lett. 125, 046401 (2020))
# Discovered and demonstrated Room-temperature quantum spin Hall edge state in a topological insulator (Nature Materials 21, 1111 (2022))
# First example of room-temperature topological quantum edge state
“Identification Procedure of Room-Temp. Quantum Spin Hall Topological Edge State”
PATENT FILING Ref#: 24-4088-1 (2024)
# Fabrication of Quantum Devices using Intrinsic Insulating Topological Materials
“Quantum device using insulating topo. material” PATENT FILING Ref#: 24-4093-1 (2024)
These research works have been featured in Physics Today, Physics World, Scientific American, Nature News, Science News, Discover magazine, New Scientist and similar media, including Physics Today’s “Search & Discovery News” multiple times over the last two decades.
Top-Ten Physics Discoveries of the last ten years by Nature Physics (2011)
Top-Ten Breakthrough of 2015 by Physics World
Several results included in modern textbooks of condensed matter physics (since 2018)
Chern number w/o Hall transport measurements..
Spin-resolved ARPES as a probe of topological quantum spin Hall effect and Berry's phase
First direct observation of Spin-textures in Topological Insulators : Spin-resolved ARPES as a probe of topological quantum spin Hall effect and Berry's phase
Intrinsic fully bulk INSULATING 3D-Topo-Insulators (Nature Physics 2014)
https://online.kitp.ucsb.edu/online/lsmatter_c15/hasan/oh/17.html
Intrinsic fully bulk INSULATING 3D-Topo-Insulators (Nature Physics 2014)
https://online.kitp.ucsb.edu/online/lsmatter_c15/hasan/oh/17.html
APS-Physics: "Topological Invariants via Spectroscopy (New Methods)
APS-Physics: "Topological Invariants via Spectroscopy (New Methods)
Topo Invariants precisely define a New Topo State of Matter which can be precisely measured via Spectroscopic measurements (no transport or quantum Hall transport is needed). This invited talk at APS-Physics elaborates this NEW method which enabled discovery of many novel topological states of matter…
KITP Lecture link .. https://www.on.kitp.ucsb.edu/online/lowdim09/hasan/oh/01.html
KITP Lecture link ..
https://www.on.kitp.ucsb.edu/online/lowdim09/hasan/oh/01.html
Unexpected and unpredicted novel (many-body, correlated) quantum phenomena in Topological Kagome Magnets & Superconductors:
Unexpected and unpredicted novel (many-body, correlated) quantum phenomena in Topological Kagome Magnets & Superconductors:
Experiments started in 2017, completed in 2017, Nature’18, NaturePhys’19, PRL’19, PRL’20, NatureCom’20a, NatureCom’20b, NatureCom’20c, Nature’20, NatureMat’21, PRL’21, Science’19, Nature’19, Nature’22a, Nature’22b, PRL’22, NaturePhys’22, NatureCom’22, NatureCom’23a, NatureCom’23b, NaturePhys’23, NatureCom’24a, NatureCom’24b, NatureCom’24c, NatureMat’24
Novel quantum phenomena in Topological kagome magnets and superconductors : https://www.nature.com/articles/s41586-022-05516-0
Theoretical Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class (Bi2Se3 class) with spin-polarized single-Dirac-cone on the surface
Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class (Bi2Se3 class) with spin-polarized single-Dirac-cone on the surface
https://arxiv.org/abs/0908.3513
Theoretical Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class (Bi2Se3 class) with spin-polarized single-Dirac-cone on the surface
Intrinsic fully bulk INSULATING 3D-Topo-Insulators (Nature Physics 2014)
https://online.kitp.ucsb.edu/online/lsmatter_c15/hasan/oh/17.html
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Weyl..
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single-Dirac-cone topology..
Intrinsic fully bulk INSULATING 3D-Topo-Insulators (Nature Physics 2014)
https://online.kitp.ucsb.edu/online/lsmatter_c15/hasan/oh/17.html
Weyl..
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Weyl topology
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New State of Matter.. ........ (3D-TI) Non-QuantumHall-like Topological Insulators
A New Paradigm : A Novel Method (Rev. of Mod. Phys. 82, 3045, 2010) for decisively measuring "Topological Invariants"
A New Paradigm : A Novel Method (Rev. of Mod. Phys. 82, 3045, 2010) for decisively measuring "Topological Invariants"
A New Paradigm : A Novel Method (see, invited review, RMP 82, 3045, 2010) for decisively measuring "topological invariants" which led to the creation of a new continent of research (the field of topological materials) with multiple groundbreaking discoveries, including topo. Dirac-Weyl fermions, Fermi arc and more..
https://journals.aps.org/rmp/abstract/10.1103/RevModPhys.82.3045
Single-Dirac-cone topology ..
Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class (Bi2Se3 class) with spin-polarized single-Dirac-cone on the surface
Theoretical Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class (Bi2Se3 class) with spin-polarized single-Dirac-cone on the surface
https://arxiv.org/abs/0908.3513
Intrinsic fully bulk INSULATING 3D-Topo-Insulators (Nature Physics 2014)
https://online.kitp.ucsb.edu/online/lsmatter_c15/hasan/oh/17.html
https://arxiv.org/abs/0908.3513 (2009) [Submitted to Nature Phys in 2008 ]
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Discovery of 2D & 3D Topological Magnets :
Discovery of 2D & 3D Topological Magnets :
Theory and Experiments : “In this talk I present our* theoretical and experimental works on 2D and 3D topological magnets in novel Weyl and Dirac materials building up on earlier result but including recent results "A three-dimensional magnetic topological phase" Ilya Belopolski et.al., arXiv:1712.09992 (2017); "Topological quantum properties of chiral crystals" Guoqing Chang et.al., Nature Materials (2018); "Topological Hopf and Chain Link Semimetal States and Their Application to Co2MnGa" Physical Review Letters 119, 156401 (2017); "Magnetic Weyl fermion semimetals in the R-AlGe family of compounds" Physical Review B (2018) and Jiaxin Yin, Songtian Zhang et.al., "Giant and anisotropic many-body spin–orbit tunability in a strongly correlated kagome magnet" NATURE 562, 91–95 (2018). *Guoqing Chang, Bahadur Singh, Su-Yang Xu, Guang Bian, Shin-Ming Huang, Chuang-Han Hsu, Ilya Belopolski, Nasser Alidoust, Daniel S Sanchez, Hao Zheng, Hong Lu, Xiao Zhang, Yi Bian, Tay-Rong Chang, Horng-Tay Jeng, Arun Bansil, Han Hsu, Shuang Jia, Titus Neupert, Hsin Lin, Jia-Xin Yin, Songtian S. Zhang, Hang Li, Kun Jiang, Bingjing Zhang, Cheng Xiang, Hao Zheng, Tyler A. Cochran, Daniel Multer, Guang Bian, Kai Liu, Zhong-Yi Lu, Ziqiang Wang, Shuang Jia, Wenhong Wang, Biao Lian, Benjamin J. Wieder, Frank Schindler, Di Wu, Titus Neupert and Tay-Rong Chang” *DOE/BES (DE-FG-02-05ER46200) and GBMF4547 (EPIQS initiative)
Quantum Frontiers ...
Topological Quantum Matter
We are exploring 2D and 3D quantum materials that feature a combination of strong correlation and topological phenomena.
This includes 2D materials that exhibit unconventional magnetism, topology, superconductivity and quantum Hall phenomena.
Topological superconductor platforms
Room Temperature topological materials
Artificial Condensed Matter Lattice, Artificial Topological Lattice
Topological kagome magnets and superconductors
Quantum spin-liquid candidates
Quantum Transport & Topology
Recent Invited Reviews:
M. Z. Hasan et al., Discovery of Topological Magnets: New Developments."https://absuploads.aps.org/presentation.cfm?pid=14503(Link is external)
- M. Z. Hasan, S.-Y. Xu, I. Belopolski, S.-M. Huang, "Discovery of Weyl Fermion Semimetals and Topological Fermi Arc States" Ann. Rev. Cond. Mat. Phys. 8, 289-309 (2017).
M. Z. Hasan et.al., "Weyl Semimetal Discovery Methods" United States Patent #10214797,
Nature Rev. Mater. 6, 784-803 (2021), Nature 612, 647-657 (2022).
S. Jia, S. Xu, M. Z. Hasan, "Weyl Semimetals, Fermi Arcs and Chiral Quantum Anomalies"
Nature Mater. 15, 1140-1144 (2016), Science 349, 613-617 (2015).
T. Neupert, M. Denner, J.-X. Yin, R. Thomale, M. Z. Hasan, "Kagome Lattice: Charge Order and Superconductivity in Kagome Materials"
Nature Physics 18, 137-143 (2022).
J. Yin, S. Pan, M. Z. Hasan, "Probing topological matter with scanning tunnelling microscopy (STM/STS),"
Nature Physics 3, 249-263 (2021)
J. Yin, B. Lian, M. Z. Hasan, "Topological Kagome Magnets & Superconductors"
Nature 612, 647-657 (2022).
Lecture Video:
“Topological Quantum Matter”
Topological Quantum Matter
Research Front-1
Topological Insulators: Discovery & Fundamental Properties
Experiments started in 2004, completed in 2007, paper submitted in 2007
2007 KITP invited talk: https://www.on.kitp.ucsb.edu/online/motterials07/hasan/(Link is external)
A topological Dirac insulator in a quantum spin Hall phase. [submitted in 2007]
D. Hsieh, D. Qian, L. Wray, et al.; (PI: M. Z. Hasan)
NATURE 452, 970 (2008). [submitted in 2007]
Electrons on the surface of Bi2Se3 form a topologically-ordered two dimensional gas with a non-trivial Berry's phase (Discovery of topological-insulator class with a single Dirac cone in 2008)
Preprint at arXiv:0812.2078 (2008)
Observation of Unconventional Quantum Spin Textures in Topological Insulators.
D. Hsieh, Y. Xia, L. Wray, et al.; (PI: M. Z. Hasan)
SCIENCE 323, 5916 (2009).
A tunable topological insulator in the spin helical Dirac transport regime.
D. Hsieh, Y. Xia, D. Qian, et al.; (PI: M. Z. Hasan)
NATURE 460, 1101 (2009).
Observation of a large-gap topological-insulator class with a single Dirac cone on the surface
Y Xia, D Qian, D Hsieh, L Wray, A Pal, H Lin et., al.
Nature Physics 5, 398-402 (2009)
Observation of Time-Reversal-Protected Single-Dirac-Cone Topological-Insulator States in Bi2X3 family
D Hsieh, Y Xia, D Qian, L Wray et., al.
Physical Review Letters 103, 146401 (2009)
Topological surface states protected from backscattering by chiral spin texture
P Roushan, J Seo, CV Parker, YS Hor, D Hsieh, D Qian et., al.
NATURE 460, 1106-1109 (2009)
Half-Heusler ternary compounds as new multifunctional experimental platforms for topological quantum phenomena
H Lin, LA Wray, Y Xia, S Xu, S Jia, RJ Cava, A Bansil, MZ Hasan
Nature Materials 9, 546-549 (2010)
Single-Dirac-Cone Topological Surface States in the TlBiSe2 Class of Topological Semiconductors
H Lin, RS Markiewicz, LA Wray, L Fu, MZ Hasan, A Bansil
Physical Review Letters 105, 036404 (2010)
A topological insulator surface under strong Coulomb, magnetic and disorder perturbations
LA Wray, SY Xu, Y Xia, D Hsieh, AV Fedorov, YS Hor, RJ Cava, A Bansil, M. Z. Hasan
Nature Physics 7, 32-37 (2011)
Topological phase transition and texture inversion in a tunable topological insulator.
S.-Y. Xu, Y. Xia, L.A. Wray, et al.; (PI: M. Z. Hasan)
SCIENCE 332, 560 (2011).
Hedgehog spin texture and Berry's phase tuning in a magnetic topological insulator.
S.-Y. Xu, M. Neupane, C. Liu, et al.; (PI: M. Z. Hasan)
Nature Physics 8, 616 (2012).
“Momentum-space imaging of Cooper pairing in a half-Dirac-gas topological
Superconductor (based on a topological insulator)”
Su-Yang Xu, N. Alidoust, I. Belopolski et.al., (PI: M. Z. Hasan)
Nature Physics 10, 943 (2014)
Observation of topological surface state quantum Hall effect in an intrinsic three-dimensional topological insulator (quantum transport in bulk insulating topological insulators)
Y Xu, I Miotkowski, C Liu, J Tian, H Nam, N Alidoust, J Hu, CK Shih, M. Z. Hasan, Y. Chen
Nature Physics 10, 956-963 (2014)
Room-temperature quantum spin Hall edge state in a higher-order topological insulator Bi4Br4
Nana Shumiya, Md Shafayat Hossain, Jia-Xin Yin et.al., (PI: M. Z. Hasan)
Nature Materials 21, 1111–1115 (2022)
A hybrid topological quantum state in an elemental solid
Md Shafayat Hossain, Frank Schindler et.al., (PI: M. Z. Hasan)
NATURE 628, 527–533 (2024).
Boundary modes of a charge density wave state in a topological material
Maksim Litskevich, Md Shafayat Hossain, S-B. Zhang, Zi-Jia Cheng et.al., (PI: M. Z. Hasan)
Nature Physics 20, 1253–1261 (2024).
Quantum transport response of topological hinge modes in a topological insulator
Md Shafayat Hossain, Qi Zhang, Zhiwei Wang, (PI: M. Z. Hasan)
Nature Physics 20, 776–782 (2024)
Research Front # 2
Topological Magnets: Discovery & Fundamental Properties
Experiments started in 2008, completed in 2008, paper submitted in 2008
Original preprint at arXiv:0812.2078(Link is external) (2008) (First Observation of Chern gap in 2012)
APS invited talk on the Discovery: https://absuploads.aps.org/presentation.cfm?pid=14503(Link is external)
A topological insulator surface under strong Coulomb, magnetic and disorder perturbations
LA Wray, SY Xu, Y Xia, D Hsieh, AV Fedorov et.al., (PI: M. Z. Hasan)
Nature Physics 7, 32-37 (2011)
(First Observation of Chern gap in 2012)
Hedgehog spin texture and Berry's phase tuning in a magnetic topological insulator.
S.-Y. Xu, M. Neupane, C. Liu, et al.; (PI: M. Z. Hasan)
Nature Physics 8, 616 (2012).
Giant and anisotropic many-body spin–orbit tunability in a correlated topo. kagome magnet
Jia-Xin Yin, Songtian S. Zhang, Hang Li et.al.; (PI: M. Z. Hasan)
NATURE 562, 91–95 (2018).
(Topological Magnetic Semimetals) Discovery of Weyl fermion lines and drumhead surface states in a room temp. topological magnet
Ilya Belopolski, K. Manna, Daniel Sanchez et.al., (PI: M. Z. Hasan)
SCIENCE 365, 1278 (2019).
Topological Chiral Crystals with Helicoid Arc Quantum States
Daniel Sanchez, Ilya Belopolski, Tyler Cochran et.al., (PI: M. Z. Hasan)
NATURE 567, 500-504 (2019).
Quantum-limit Chern topological magnet
J-X. Yin, S.S. Zhang et.al., (PI: M. Z. Hasan)
NATURE 583, 533–536 (2020).
Rare Earth Engineering in RMn6Sn6 (R=Gd−Tm, Lu) Topological Kagome Magnets.
Wenlong Ma, Xitong Xu, Jia-Xin Yin et.al.,
Phys. Rev. Lett. 126, 246602 (2021).
“Observation of a linked loop quantum state in a topological magnet”
I. Belopolski, G. Chang, T. Cochran etal., (PI: M. Z. Hasan)
NATURE 604, 647-652 (2022)
A topological Hund nodal line antiferromagnet
Xian P. Yang, Yueh-Ting Yao, Pengyu Zheng et.al., (PI: M. Z. Hasan)
Nature Commun. 15, 7052 (2024)
Research Front # 3
Topological Weyl/Dirac semimetals: Discovery & Fundamental Properties
Experiments started in 2011, completed in 2014
APS invited talk on the Discovery: https://absuploads.aps.org/presentation.cfm?pid=14503(Link is external)
Topological phase transition and texture inversion (at 3D bulk Dirac point) in a tunable topological insulator.
S.-Y. Xu, Y. Xia, L.A. Wray, et al.; (PI: M. Z. Hasan)
SCIENCE 332, 560 (2011).
Observation of Fermi Arc Surface States in a Topological Metal.
S.-Y. Xu, C. Liu, S K. Kushwaha et.al., (PI: M. Z. Hasan)
SCIENCE 347, 294 (2015). (paper submitted in 2014)
Discovery of a Weyl Fermion semimetal and topological Fermi arcs.
S.-Y. Xu, I. Belopolski, N. Alidoust et.al., (PI: M. Z. Hasan)
SCIENCE 349, 613 (2015).
Discovery of topo. Weyl fermion lines and drumhead surface states in a room temp. magnet
Ilya Belopolski, K. Manna, Daniel Sanchez et.al., (PI: M. Z. Hasan)
SCIENCE 365, 1278 (2019).
Giant and anisotropic many-body spin–orbit tunability in a correlated kagome magnet
Jia-Xin Yin, Songtian S. Zhang, Hang Li et.al.; (PI: M. Z. Hasan)
NATURE 562, 91–95 (2018).
Topological Chiral Crystals with Helicoid Arc Quantum States (Topological Semimetals)
Daniel Sanchez, Ilya Belopolski, Tyler Cochran et.al., (PI: M. Z. Hasan)
NATURE 567, 500-504 (2019).
Coexistence of Bulk-Nodal and Surface-Nodeless Cooper Pairings in a Superconducting Dirac Semimetal.
Yang, X.P., Zhong, Y., Mardanya, S., Cochran, T.A., Chapai, R., Mine, A., Zhang, J., Sánchez-Barriga, J., Cheng, Z-J., Clark, O.J., Yin, J-X., Blawat, J., Cheng, G., Belopolski, I., Nagashima, T., Najafzadeh, S., Gao, S., Yao, N., Bansil, A., Jin, R., Chang, T-R., Shin, S., Okazaki, K. & Hasan, M.Z.
Phys. Rev. Lett. 130, 046402 (2023).
Tunable topologically driven Fermi arc van Hove singularities.
Sanchez, D.S., Cochran, T.A., Belopolski, I., Cheng, Z-J., Yang, X.P., Liu, Y., Hou, T., Xu, X., Manna, K., Shekhar, C., Yin, J-X., Borrmann, H., Chikina, A., Denlinger, J.D., Stro cov, V.N., Xie, W., Felser, C., Jia, S., Chang, G. & Hasan, M.Z.
Nature Physics 19, 682 (2023).
Causal structure of interacting Weyl fermions in condensed matter systems.
Chiu, W-C., Chang, G., Macam, G., Belopolski, I., Huang, S-M., Markiewicz, R., Yin, J-X., Cheng, Z-J., Lee, C-C., Chang, T-R., Chuang, F-C., Xu, S-Y., Lin, H., Hasan, M.Z.& Bansil, A.
Nature Commun. 14, 2228 (2023).
Visualizing Higher-Fold Topology in Chiral Crystals.
Cochran, T.A., Belopolski, I., Manna, et.al., (PI: M. Z. Hasan)
Phys. Rev. Lett. 130, 066402 (2023)
A hybrid topological quantum state in an elemental solid
Md Shafayat Hossain, Frank Schindler et.al., (PI: M. Z. Hasan)
NATURE 628, 527–533 (2024).
Research Front # 4
Topological Kagome Magnets & Superconductors
Opened several new unexpected research fronts in topological kagome research ..
Giant and anisotropic many-body spin–orbit tunability in a correlated kagome magnet
Jia-Xin Yin, Songtian S. Zhang, Hang Li et.al.; (PI: M. Z. Hasan)
NATURE 562, 91–95 (2018).
Quantum-limit Chern topological magnet (kagome magnet)
J-X. Yin, S.S. Zhang et.al., (PI: M. Z. Hasan)
NATURE 583, 533–536 (2020).
Unconventional chiral charge order in kagome superconductor KV3Sb5.
Yu-Xiao Jiang, Jia-Xin Yin, M. Michael Denner, Nana Shumiya, Brenden R. Ortiz, Gang Xu, Zurab Guguchia, Junyi He, Md Shafayat Hossain, Xiaoxiong Liu, Jacob Ruff, Linus Kautzsch, Songtian S. Zhang, Guoqing Chang, Ilya Belopolski, Qi Zhang, Tyler A. Cochran, Daniel Multer, Maksim Litskevich, Zi-Jia Cheng, Xian P. Yang, Ziqiang Wang, Ronny Thomale, Titus Neupert, Stephen D. Wilson, M. Zahid Hasan.
Nature Materials 20, 1353–1357 (2021).
Rare Earth Engineering in RMn6Sn6 (R=Gd−Tm, Lu) Topological Kagome Magnets.
Wenlong Ma, Xitong Xu, Jia-Xin Yin et.al.,
Phys. Rev. Lett. 126, 246602 (2021).
Time-reversal symmetry-breaking charge order in a kagome superconductor
C. Mielke, D. Das, Jia-Xin Yin et.al., (Co-PI: M. Z. Hasan)
NATURE 602, 245 (2022)
Topological Kagome Magnets and Superconductors
J. Yin, B. Lian, M. Z. Hasan
NATURE 612, 647-657 (2022)
“Discovery of charge order and corresponding edge state in kagome magnet FeGe”
Jia-Xin Yin, Yu-Xiao Jiang, Xiaokun Teng, Md. Shafayat Hossain et.al., (PI: M. Z. Hasan)
Phys. Rev. Lett. 129, 166401 (2022)
“Charge order and superconductivity in kagome materials”
T. Neupert, M. Denner, J.-X. Yin, R. Thomale & M. Z. Hasan
Nature Physics 18, 137 (2022)
Discovery of conjoined charge density waves in the kagome superconductor CsV3Sb5
H Li, G Fabbris, AH Said, JP Sun, YX Jiang, JX Yin, et.al.,
Nature Commun. 13, 6348 (2022)
Discovery of charge density wave in a correlated kagome lattice antiferromagnet
X. Teng, L. Chen, F. Ye et.al.,
NATURE 609, 490-495 (2022)
Tunable unconventional kagome superconductivity in charge ordered RbV3Sb5 and KV3Sb5.
Guguchia, Z., Mielke III, C., Das, D., Gupta, R., Yin, J-X., et.al.,
Nature Commun. 14, 153 (2023).
Hidden magnetism uncovered in charge ordered bilayer kagome material
Z. Guguchia, D. J. Gawryluk, Soohyeon Shin, Z. Hao, et.al.,
Nature Commun. 14, 7796 (2023)
Tunable topologically driven Fermi arc van Hove singularities.
Sanchez, D.S., Cochran, T.A., Belopolski, I., et.al., (PI: M. Z. Hasan)
Nature Physics 19, 682 (2023).
Visualizing Higher-Fold Topology in Chiral Crystals.
Cochran, T.A., Belopolski, I., Manna, K., Yahyavi, M., Liu, Y., Sanchez, D.S., Yang, X.P., Multer, D., Yin, J-X., Borrmann, H., Chikina, A., Krieger, J.A., Sánchez-Barriga, J., Le Fèvre, P., Bertran, F., Strocov, V.N., Denlinger, J.D., Chang, T-R., Jia, S., Felser, C., Lin, H., Chang, G. & Hasan, M.Z.
Phys. Rev. Lett. 130, 066402 (2023)
Tunable topologically driven Fermi arc van Hove singularities.
Sanchez, D.S., Cochran, T.A., Belopolski, I., Cheng, Z-J., Yang, X.P., Liu, Y., Hou, T., Xu, X., Manna, K., Shekhar, C., Yin, J-X., Borrmann, H., Chikina, A., Denlinger, J.D., Stro cov, V.N., Xie, W., Felser, C., Jia, S., Chang, G. & Hasan, M.Z.
Nature Physics 19, 682 (2023).
Charge density wave in topological kagome metal ScV6Sn6
Yong Hu, Junzhang Ma, Yinxiang Li et.al.,
Nature Commun 15, 1658 (2024)
Depth-dependent study of time-reversal symmetry-breaking in the kagome superconductor AV3Sb5
J. N. Graham, C. Mielke III, D. Das et.al.,
Nature Commun 15, 8978 (2024).
A topological Hund nodal line antiferromagnet
Xian P. Yang, Yueh-Ting Yao, Pengyu Zheng et.al., (PI: M. Z. Hasan)
Nature Commun. 15, 7052 (2024)
Van Hove annihilation and nematic instability on a kagome lattice
Yu-Xiao Jiang, Sen Shao, Wei Xia, M. Michael Denner et.al., (PI: M. Z. Hasan)
Nature Materials (2024). https://doi.org/10.1038/s41563-024-01914-z
KITP Lecture link .. https://www.on.kitp.ucsb.edu/online/lowdim09/hasan/oh/01.html
KITP Lecture link ..
https://www.on.kitp.ucsb.edu/online/lowdim09/hasan/oh/01.html
Fermi-Arcs: Discovery of Fermi-Arc (Dirac-string) states in Topo Metals..
Fermi-Arcs: Discovery of Fermi-Arc (Dirac-string) states in Topo Metals..
Science (2014)
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single-Dirac-cone topology..
Intrinsic fully bulk INSULATING 3D-Topo-Insulators (Nature Physics 2014)
https://online.kitp.ucsb.edu/online/lsmatter_c15/hasan/oh/17.html
Discovery of 2D & 3D Topological Magnets :
Discovery of 2D & 3D Topological Magnets :
Theory and Experiments : “In this talk I present our* theoretical and experimental works on 2D and 3D topological magnets in novel Weyl and Dirac materials building up on earlier result but including recent results "A three-dimensional magnetic topological phase" Ilya Belopolski et.al., arXiv:1712.09992 (2017); "Topological quantum properties of chiral crystals" Guoqing Chang et.al., Nature Materials (2018); "Topological Hopf and Chain Link Semimetal States and Their Application to Co2MnGa" Physical Review Letters 119, 156401 (2017); "Magnetic Weyl fermion semimetals in the R-AlGe family of compounds" Physical Review B (2018) and Jiaxin Yin, Songtian Zhang et.al., "Giant and anisotropic many-body spin–orbit tunability in a strongly correlated kagome magnet" NATURE 562, 91–95 (2018). *Guoqing Chang, Bahadur Singh, Su-Yang Xu, Guang Bian, Shin-Ming Huang, Chuang-Han Hsu, Ilya Belopolski, Nasser Alidoust, Daniel S Sanchez, Hao Zheng, Hong Lu, Xiao Zhang, Yi Bian, Tay-Rong Chang, Horng-Tay Jeng, Arun Bansil, Han Hsu, Shuang Jia, Titus Neupert, Hsin Lin, Jia-Xin Yin, Songtian S. Zhang, Hang Li, Kun Jiang, Bingjing Zhang, Cheng Xiang, Hao Zheng, Tyler A. Cochran, Daniel Multer, Guang Bian, Kai Liu, Zhong-Yi Lu, Ziqiang Wang, Shuang Jia, Wenhong Wang, Biao Lian, Benjamin J. Wieder, Frank Schindler, Di Wu, Titus Neupert and Tay-Rong Chang” *DOE/BES (DE-FG-02-05ER46200) and GBMF4547 (EPIQS initiative)
A New State of Matter ...
Intrinsic fully bulk INSULATING 3D-Topo-Insulators (Nature Physics 2014)
Intrinsic fully bulk INSULATING 3D-Topo-Insulators (Nature Physics 2014)
https://online.kitp.ucsb.edu/online/lsmatter_c15/hasan/oh/17.html
APS-Physics: "Topological Invariants via Spectroscopy (New Methods)
APS-Physics: "Topological Invariants via Spectroscopy (New Methods)
Topo Invariants precisely define a New Topo State of Matter which can be precisely measured via Spectroscopic measurements (no transport or quantum Hall transport is needed). This invited talk at APS-Physics elaborates this NEW method which enabled discovery of many novel topological states of matter…
Recent results ...
KITP Lecture link .. https://www.on.kitp.ucsb.edu/online/lowdim09/hasan/oh/01.html
KITP Lecture link ..
https://www.on.kitp.ucsb.edu/online/lowdim09/hasan/oh/01.html
Unexpected and unpredicted novel (many-body, correlated) quantum phenomena in Topological Kagome Magnets & Superconductors:
Unexpected and unpredicted novel (many-body, correlated) quantum phenomena in Topological Kagome Magnets & Superconductors:
Experiments started in 2017, completed in 2017, Nature’18, NaturePhys’19, PRL’19, PRL’20, NatureCom’20a, NatureCom’20b, NatureCom’20c, Nature’20, NatureMat’21, PRL’21, Science’19, Nature’19, Nature’22a, Nature’22b, PRL’22, NaturePhys’22, NatureCom’22, NatureCom’23a, NatureCom’23b, NaturePhys’23, NatureCom’24a, NatureCom’24b, NatureCom’24c, NatureMat’24
Novel quantum phenomena in Topological kagome magnets and superconductors : https://www.nature.com/articles/s41586-022-05516-0
Theoretical Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class (Bi2Se3 class) with spin-polarized single-Dirac-cone on the surface
Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class (Bi2Se3 class) with spin-polarized single-Dirac-cone on the surface
https://arxiv.org/abs/0908.3513
Theoretical Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class (Bi2Se3 class) with spin-polarized single-Dirac-cone on the surface
KITP Lecture .. https://www.on.kitp.ucsb.edu/online/lowdim09/hasan/oh/05.html
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Advanced Spectroscopy
We utilize and develop advanced state-of-the-art spectroscopic and microscopic techniques such as low temperature ARPES, spin-ARPES, STM, STS and ultrafast optical & THz, MBE-STM techniques to explore charge, spin, orbital and lattice degrees of freedom in novel quantum topological and strongly correlated matter.
We are currently developing new experimental methods.
Please visit the lab to learn more about experimental details and instrumental capabilities.
CO-LEAD Proposer (Adv. Instrumentation):
MERLIN Beamline & ADv. SPECTROSCOPY
ARPES End-Station/BL: "MERLIN - A meV Resolution Beamline at the Advanced Light Source (Berkeley Lab)," AIP Conf. Proc. 879, 509 (2007). With MERLIN collaboration, M. Z. Hasan et al., "Design of an elliptically bent refocus mirror for the MERLIN beamline at the Advanced Light Source (Berkeley Lab)," Nucl. Instrum. Methods Phys. Res. A 582, 135 (2007).
Nuclear Instruments and Methods in Physics Research Section A Accelerators, Spectrometers, Detectors and Associated Equipment 582(1): 135-137 (2007)
Berkeley Lab: https://newscenter.lbl.gov/2017/04/14/how-x-rays-pushed-topological-mat…(Link is external)
STM/STS technique Review:
"Probing topological matter with scanning tunnelling microscopy (STM/STS)"
J. Yin, S. Pan and M.Z. Hasan
Nature Reviews Physics 3, 249-263 (2021)
"Discovery of a Quantum Limit Chern Magnet" and related STM/STS papers:
Nature 583, 533-536 (2020).
Nature 612, 647–657 (2022)
Nature 628, 527-533 (2024).
Experimental signatures of phase interference and sub-femtosecond time dynamics on the incident energy axis of resonant inelastic x-ray scattering
Laser-based SPCM: Polarization-dependent mid-infrared photo-current microscopy technique
Nature Commun. 16: 3782 (2025)
Inventions, Breakthroughs & Patents :
# Developed methods for determining Z2 topological invariants and Mirror Chern numbers from spin-ARPES experiments alone without referring to theory (Nature 2009, Science 2009, Science 2011). These detailed methods were used to demonstrate that the 3D Topological Insulators are a new and distinct state of matter, which cannot be reduced to multiple copies of IQH, and there is no spin Hall effect in 3D. The 3D state is thus an example of non-quantum-Hall-like topological matter and the first realization of topologically ordered bulk solid in nature (Physics World 2011, Physics Today 2010).
# Demonstrated that electrons on the surface of some spin-orbit materials form a topologically-ordered two dimensional gas with a non-trivial Berry's phase (arXiv:0812.2078 (2008), Nature 2009)
# Developed methods for the demonstration of spin-momentum locking without utilizing any transport method (Nature 2009, Science 2009, Science 2011)
# Developed methods for the determination of Chern invariant and Chern gap from spin-ARPES experiments (Nature Physics 2012)
# Developed methods and algorithms for the identification of chiral fermions (Weyl and other chiral fermions) from spectroscopic experiments without replying on band-structure measurements (Science 2015a, Nature Physics 2015, Science 2015b)
# Developed methods and algorithms for the identification of Fermi arc fermions "Criteria for Directly Detecting (Proving) Topological Fermi Arcs" (Phys. Rev. Lett. 116, 066802 (2016))
# Demonstrated methods and algorithms for “Momentum-space imaging of Cooper pairing in a half-Dirac-gas Superconductor (based on a topological insulator)” (Nature Physics 10, 943 (2014))
# Demonstrated Adiabatic continuation approach to theoretically predict topo. materials Working with Hsin Lin demonstrated that first-principles-based adiabatic continuation approach is a powerful and efficient tool for constructing topological phase diagrams and locating non-trivial topological insulator materials. Applied to real materials, results demonstrated the efficacy of adiabatic continuation for exploring topologically nontrivial alloying systems and for identifying new topological insulators even when the underlying lattice does not possess inversion symmetry, and the approaches based on parity analysis of Fu-Kane methods are not viable. (Nature Materials 9, 546 (2010); Phys. Rev. B 87, 121202(R) (2013).)
# Discovery (Theoretical Prediction & Experimental Demonstration) of Weyl semimetals -- Weyl fermion and topological Fermi arcs in spin-orbit materials (Science 349, 613 (2015); Science 347, 294 (2015). Nature Phys 11, 748 (2015))
# Developed and demonstrated a novel artificial condensed matter lattice and a new platform for one-dim. topological phases (Science Advances 3, e1501692 (2017))
# Demonstrated quantum transport in bulk insulating topological insulators and Quantum transport response of topological hinge modes in a topological insulator (Nature Physics 20, 776–782 (2024) and Nature Physics 10, 956-963 (2014))
# First Observation of Chern gap in 2012 Hedgehog spin texture and Berry's phase tuning in a magnetic topological insulator (Nature Physics 8, 616 (2012))
# First example of Weyl semimetals and the methods for its discovery US Patent#10214797 “Method for production and identification of Weyl semimetal” (2016)
# Discovered and demonstrated Topological nodal-line (continuous Dirac/Weyl) semimetals (2015-2016) Led in the theoretical prediction and experimental discovery of topological nodal-line semimetals (Nature Commun (2016), arXiv 2015) and elucidated their nontrivial topological electronic structure including Dirac loop Fermi surfaces known as nodal rings (demonstrated in PbTaSe2 and TlTaSe2) (Nature Commun. 7:10556 (2016); Physical Review B (2016))
# Demonstrated Giant and anisotropic many-body spin–orbit tunability in a correlated topo. kagome magnet (NATURE 562, 91–95 (2018))
# Demonstrated Quantum-limit Chern topological magnet (NATURE 583, 533 (2020))
# Demonstrated Magnetic-field control of topological electronic response near room temperature in correlated Kagome magnets (Physical Review Letters 123, 196604 (2019))
# Demonstrated Many-body Resonance in a Correlated Topological Kagome Antiferromagnet (Phys. Rev. Lett. 125, 046401 (2020))
# Discovered and demonstrated Room-temperature quantum spin Hall edge state in a topological insulator (Nature Materials 21, 1111 (2022))
# First example of room-temperature topological quantum edge state
“Identification Procedure of Room-Temp. Quantum Spin Hall Topological Edge State”
PATENT FILING Ref#: 24-4088-1 (2024)
# Fabrication of Quantum Devices using Intrinsic Insulating Topological Materials
“Quantum device using insulating topo. material” PATENT FILING Ref#: 24-4093-1 (2024)
These research works have been featured in Physics Today, Physics World, Scientific American, Nature News, Science News, Discover magazine, New Scientist and similar media, including Physics Today’s “Search & Discovery News” multiple times over the last two decades.
Top-Ten Physics Discoveries of the last ten years by Nature Physics (2011)
Top-Ten Breakthrough of 2015 by Physics World
Several results included in modern textbooks of condensed matter physics (since 2018)
KITP Lecture link .. https://www.on.kitp.ucsb.edu/online/lowdim09/hasan/oh/01.html
KITP Lecture link ..
https://www.on.kitp.ucsb.edu/online/lowdim09/hasan/oh/01.html
A New Paradigm : A Novel Method (Rev. of Mod. Phys. 82, 3045, 2010) for decisively measuring "Topological Invariants"
A New Paradigm : A Novel Method (Rev. of Mod. Phys. 82, 3045, 2010) for decisively measuring "Topological Invariants"
A New Paradigm : A Novel Method (see, invited review, RMP 82, 3045, 2010) for decisively measuring "topological invariants" which led to the creation of a new continent of research (the field of topological materials) with multiple groundbreaking discoveries, including topo. Dirac-Weyl fermions, Fermi arc and more..
https://journals.aps.org/rmp/abstract/10.1103/RevModPhys.82.3045
New Methods ...
Big Picture ..
Unexpected and unpredicted novel (many-body, correlated) quantum phenomena in Topological Kagome Magnets & Superconductors:
Unexpected and unpredicted novel (many-body, correlated) quantum phenomena in Topological Kagome Magnets & Superconductors:
Experiments started in 2017, completed in 2017, Nature’18, NaturePhys’19, PRL’19, PRL’20, NatureCom’20a, NatureCom’20b, NatureCom’20c, Nature’20, NatureMat’21, PRL’21, Science’19, Nature’19, Nature’22a, Nature’22b, PRL’22, NaturePhys’22, NatureCom’22, NatureCom’23a, NatureCom’23b, NaturePhys’23, NatureCom’24a, NatureCom’24b, NatureCom’24c, NatureMat’24
Novel quantum phenomena in Topological kagome magnets and superconductors (Nature 2022) :
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Discovery of 2D & 3D Topological Magnets :
Discovery of 2D & 3D Topological Magnets :
Theory and Experiments : “In this talk I present our* theoretical and experimental works on 2D and 3D topological magnets in novel Weyl and Dirac materials building up on earlier result but including recent results "A three-dimensional magnetic topological phase" Ilya Belopolski et.al., arXiv:1712.09992 (2017); "Topological quantum properties of chiral crystals" Guoqing Chang et.al., Nature Materials (2018); "Topological Hopf and Chain Link Semimetal States and Their Application to Co2MnGa" Physical Review Letters 119, 156401 (2017); "Magnetic Weyl fermion semimetals in the R-AlGe family of compounds" Physical Review B (2018) and Jiaxin Yin, Songtian Zhang et.al., "Giant and anisotropic many-body spin–orbit tunability in a strongly correlated kagome magnet" NATURE 562, 91–95 (2018). *Guoqing Chang, Bahadur Singh, Su-Yang Xu, Guang Bian, Shin-Ming Huang, Chuang-Han Hsu, Ilya Belopolski, Nasser Alidoust, Daniel S Sanchez, Hao Zheng, Hong Lu, Xiao Zhang, Yi Bian, Tay-Rong Chang, Horng-Tay Jeng, Arun Bansil, Han Hsu, Shuang Jia, Titus Neupert, Hsin Lin, Jia-Xin Yin, Songtian S. Zhang, Hang Li, Kun Jiang, Bingjing Zhang, Cheng Xiang, Hao Zheng, Tyler A. Cochran, Daniel Multer, Guang Bian, Kai Liu, Zhong-Yi Lu, Ziqiang Wang, Shuang Jia, Wenhong Wang, Biao Lian, Benjamin J. Wieder, Frank Schindler, Di Wu, Titus Neupert and Tay-Rong Chang” *DOE/BES (DE-FG-02-05ER46200) and GBMF4547 (EPIQS initiative)
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Bose-Einstein centenary lectures
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Theory & Modelling
Topological Quantum Science and Engineering: Hasan lab helped launch the field of Topological Insulators by directly detecting the novel surface states and thoroughly demonstrating their unusual topological properties using advanced spin-sensitive spectroscopic techniques (50,000+ citations). Subsequently, Hasan group has theoretically and experimentally discovered many novel classes of topological matter and topological phase transitions including Topological Magnets (via the demonstration of Chern gap in 2012) using novel instrumentations and innovative methods and introduced designed discovery methods. The field expanded to include topological semimetals, notably Weyl Semimetals, whose states mimic massless fermions considered in quantum field theory. In 2015 Hasan group observed the emergent Weyl fermions and novel topological Fermi arc surface states in several topological semimetals he and his team theoretically predicted in arsenide and other materials. His Weyl fermion work is based on his and his team's theoretical predictions in several spin-orbit materials. Subsequently, he has theoretically and experimentally discovered many novel classes of magnetic topological semimetals. He has also made groundbreaking contributions (theoretical and experimental) in the subfields of topological phase transitions, topological magnets in 2D and 3D, topological nodal-line and drumhead metals, topological magnetic semimetals, topological chiral crystals, topological Hopf link semimetals, topological superconductors, Helicoid-arc quantum states and Kagome magnets and materials, Chern magnets and charge-ordered Kagome superconductors enabled by innovative applications and development of experimental methods. He identified room temperature topological materials. A vast majority of his experimental discoveries are based on his and his team's theoretical predictions of topological materials. These materials are broadly important for future device applications with higher energy efficiency, as quantum information science platforms, and for exploring new emergent or many-body quantum physics. He has also contributed to the conceptual design and theoretical development of some of these topics and written several comprehensive review articles by invitation. The methodologies introduced by him to explore and discover topological materials and phenomena are being used by others world-wide to further advance the field and led to new discoveries. His experiments and methods have been seminal in giving rise to the field of "Topological Quantum Matter" with more than 90,000 citations (over 250 publications with h-factor 105+), which is now growing vigorously at the nexus of condensed matter physics, materials engineering, nano-science, device physics & quantum engineering, chemistry and relativistic quantum field theory as evidenced in all citation tracks.
Quantum many-body physics
Quantum many-body physics in doped Mott insulators, Charge-order and Superconductivity competition, Nematic order & fluctuations etc. (Hasan lab research)
Hasan et.al., Phys. Rev. Lett. 92, 246402 (2004); Phys. Rev. Lett. 96, 046407 (2006); Phys. Rev. Lett. 97, 186405 (2006); Phys. Rev. Lett. 96, 216405 (2006). Phys. Rev. Lett. 98, 117007 (2007) and Phys. Rev. Lett. 99, 167002 (2007). Phys. Rev. B 78, 184508 (2008); Phys. Rev. Lett. 103, 037002 (2009). Nature’18, NaturePhys’19, PRL’19, PRL’20, NatureCom’20a, NatureCom’20b, NatureCom’20c, Nature’20, NatureMat’21, PRL’21, Science’19, Nature’19, Nature’22a, Nature’22b, PRL’22, NaturePhys’22, NatureCom’22, NatureCom’23a, NatureCom’23b, NaturePhys’23, NatureCom’24a, NatureCom’24b, NatureCom’24c, NatureMat’24, NaturePhysics'25
KITP Lecture link .. https://www.on.kitp.ucsb.edu/online/lowdim09/hasan/oh/01.html
KITP Lecture link ..
https://www.on.kitp.ucsb.edu/online/lowdim09/hasan/oh/01.html
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Research Highlights
Discovery of Topological surface states
https://newscenter.lbl.gov/2017/04/14/how-x-rays-pushed-topological-matter-research-over-the-top/
https://absuploads.aps.org/presentation.cfm?pid=14503
Discovery of Topological magnets and topological chiral phenomena
https://arxiv.org/abs/1812.04466(Link is external)
https://absuploads.aps.org/presentation.cfm?pid=14503
Discovery of Topological Weyl phenomena
https://www.amacad.org/person/m-zahid-hasan(Link is external)
Discovery of novel quantum phenomena in Topological kagome magnets and superconductors
https://research.princeton.edu/news/princeton-led-team-discovers-unexpe…(Link is external)
https://www.nature.com/articles/s41586-022-05516-0(Link is external) (Link opens in new window)
Theoretical Prediction and experimental discovery of novel topological materials and quantum phenomena
https://www.amacad.org/person/m-zahid-hasan(Link is external)
New Phases of Matter :
According1 to U.S. Department of Energy, these “experiments led to seminal discoveries of new phases of matter and new fermionic quasiparticles.” The research work on topological quantum matter “opened new areas in condensed matter physics and holds promise for future transformative applications in materials sciences”
Non-QuantumHall-like Topological Matter
Hasan, M. Z., Xu, S.-Y. & Bian, G.
Topological insulators, topological superconductors and Weyl fermion semimetals: discoveries, perspectives and outlooks.
Phys. Scr. 2015, 014001 (2015).
“.. recent experimental discoveries of non-quantum-Hall-like topological insulators, topological superconductors, Weyl semimetals and other topological states of matter also signal a clear departure from the quantum-Hall-effect-like transport paradigm that has dominated the field since the 1980s. It is these new forms of matter that enabled realizations of topological-Dirac, Weyl cones, helical-Cooper-pairs, Fermi-arc-quasiparticles and other emergent phenomena in fine-tuned photoemission (ARPES) experiments since ARPES experiments directly allow the study of bulk-boundary (topological) correspondence. In this proceeding we provide a brief overview of the key experiments and discuss our perspectives regarding the new research frontiers enabled by these experiments. Taken collectively, we argue in favor of the emergence of 'topological-condensed-matter-physics' in laboratory experiments...” (Non-QuantumHall-like Topological Matter)
Intrinsic fully bulk INSULATING 3D-Topo-Insulators (Nature Physics 2014)
Intrinsic fully bulk INSULATING 3D-Topo-Insulators (Nature Physics 2014)
https://online.kitp.ucsb.edu/online/lsmatter_c15/hasan/oh/17.html
APS-Physics: "Topological Invariants via Spectroscopy (New Methods)
APS-Physics: "Topological Invariants via Spectroscopy (New Methods)
Topo Invariants precisely define a New Topo State of Matter which can be precisely measured via Spectroscopic measurements (no transport or quantum Hall transport is needed). This invited talk at APS-Physics elaborates this NEW method which enabled discovery of many novel topological states of matter…
KITP Lecture link .. https://www.on.kitp.ucsb.edu/online/lowdim09/hasan/oh/01.html
KITP Lecture link ..
https://www.on.kitp.ucsb.edu/online/lowdim09/hasan/oh/01.html
KITP Lecture link .. https://www.on.kitp.ucsb.edu/online/lowdim09/hasan/oh/01.html
Unexpected and unpredicted novel (many-body, correlated) quantum phenomena in Topological Kagome Magnets & Superconductors:
Unexpected and unpredicted novel (many-body, correlated) quantum phenomena in Topological Kagome Magnets & Superconductors:
Experiments started in 2017, completed in 2017, Nature’18, NaturePhys’19, PRL’19, PRL’20, NatureCom’20a, NatureCom’20b, NatureCom’20c, Nature’20, NatureMat’21, PRL’21, Science’19, Nature’19, Nature’22a, Nature’22b, PRL’22, NaturePhys’22, NatureCom’22, NatureCom’23a, NatureCom’23b, NaturePhys’23, NatureCom’24a, NatureCom’24b, NatureCom’24c, NatureMat’24
Novel quantum phenomena in Topological kagome magnets and superconductors : https://www.nature.com/articles/s41586-022-05516-0
Hasan group theoretical discoveries ...
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Unexpected and unpredicted novel (many-body, correlated) quantum phenomena in Topological Kagome Magnets & Superconductors:
Unexpected and unpredicted novel (many-body, correlated) quantum phenomena in Topological Kagome Magnets & Superconductors:
Experiments started in 2017, completed in 2017, Nature’18, NaturePhys’19, PRL’19, PRL’20, NatureCom’20a, NatureCom’20b, NatureCom’20c, Nature’20, NatureMat’21, PRL’21, Science’19, Nature’19, Nature’22a, Nature’22b, PRL’22, NaturePhys’22, NatureCom’22, NatureCom’23a, NatureCom’23b, NaturePhys’23, NatureCom’24a, NatureCom’24b, NatureCom’24c, NatureMat’24
Novel quantum phenomena in Topological kagome magnets and superconductors (Nature 2022) :
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Discovery of 2D & 3D Topological Magnets :
Discovery of 2D & 3D Topological Magnets :
Theory and Experiments : “In this talk I present our* theoretical and experimental works on 2D and 3D topological magnets in novel Weyl and Dirac materials building up on earlier result but including recent results "A three-dimensional magnetic topological phase" Ilya Belopolski et.al., arXiv:1712.09992 (2017); "Topological quantum properties of chiral crystals" Guoqing Chang et.al., Nature Materials (2018); "Topological Hopf and Chain Link Semimetal States and Their Application to Co2MnGa" Physical Review Letters 119, 156401 (2017); "Magnetic Weyl fermion semimetals in the R-AlGe family of compounds" Physical Review B (2018) and Jiaxin Yin, Songtian Zhang et.al., "Giant and anisotropic many-body spin–orbit tunability in a strongly correlated kagome magnet" NATURE 562, 91–95 (2018). *Guoqing Chang, Bahadur Singh, Su-Yang Xu, Guang Bian, Shin-Ming Huang, Chuang-Han Hsu, Ilya Belopolski, Nasser Alidoust, Daniel S Sanchez, Hao Zheng, Hong Lu, Xiao Zhang, Yi Bian, Tay-Rong Chang, Horng-Tay Jeng, Arun Bansil, Han Hsu, Shuang Jia, Titus Neupert, Hsin Lin, Jia-Xin Yin, Songtian S. Zhang, Hang Li, Kun Jiang, Bingjing Zhang, Cheng Xiang, Hao Zheng, Tyler A. Cochran, Daniel Multer, Guang Bian, Kai Liu, Zhong-Yi Lu, Ziqiang Wang, Shuang Jia, Wenhong Wang, Biao Lian, Benjamin J. Wieder, Frank Schindler, Di Wu, Titus Neupert and Tay-Rong Chang” *DOE/BES (DE-FG-02-05ER46200) and GBMF4547 (EPIQS initiative)
Recent Research
Topological Magnets & Superconductors
J. Yin, B. Lian, M. Z. Hasan, "Topological Kagome Magnets and Superconductors,"
Nature 612, 647-657 (2022).
Nature 602, 245-250 (2022).
Weyl & Chiral phenomena
S. Jia, S.-Y. Xu, and M. Z. Hasan, "Weyl Semimetals, Fermi Arcs and Chiral Anomalies,"
Nature Mater. 15, 1140–1144 (2016).
Nature Reviews Materials 6, 784–803 (2021)
Nature 604, 647-652 (2022).
ARPES & STM/STS Reviews
"Probing topological matter with scanning tunnelling microscopy (STM)," Nat. Rev. Phys. 3, 249-263 (2021).
"Topological Insulators, Topological Superconductors and Weyl Semimetals," Phys. Scr. T164, 014001 (2015).
Nature Reviews Physics 3, 249–263 (2021)
Charge-order & Superconductivity
T. Neupert, M. Denner, J. Yin, R. Thomale, M. Z. Hasan, "Charge-order and Superconductivity in Kagome Lattice Materials," Nature Phys. (2021).
K. Jiang et al., "Kagome Superconductors AV3Sb5," https://arxiv.org/abs/2109.10809.
Nature Phys. 18, 137-143 (2022).
Chiral Crystals & Helicoidal physics
Chang et al., "Topological Quantum Properties of Chiral Crystals,"
Nature Mater. 17, 978-985 (2018).
"Discovery of Topological Chiral Crystals with Helicoid Arc Quantum States," https://arxiv.org/abs/1812.04466.
Nature 567, 500-505 (2019)
2D Materials & Quantum Devices
The magnetic genome of two-dimensional van der Waals materials ACS nano 16 (5), 6960-7079 (2022)
Tunable superconductivity coexisting with the anomalous Hall effect in 1T'-WS2; https://arxiv.org/abs/2501.05980
Transport response of topological hinge modes
Nature Physics 20, 776–782 (2024)
Novel Topological Matter
Belopolski et al., "Observation of a Linked Loop Quantum State in a Topological Magnet,"
Nature 604, 647-652 (2022).
Novel Topological Matter: Discovery of a hybrid topological quantum state
Nature 628, 527 (2024)
Quantum Transport & Topology
Topological Quantum Transport : Transport response of topological hinge modes
Nature Physics 20, 776–782 (2024)
Room T Topo Phenomena
Chang, Xu et al., "Room-temperature Magnetic Weyl Semimetal and Nodal Line Semimetal States in Co2TiX" https://arxiv.org/abs/1603.01255
Room-temperature quantum spin Hall edge state in a topological insulator
Nature Materials 21, 1111–1115 (2022)
Ultrafast quantum phenomena
Unconventional photocurrent responses from chiral surface Fermi arcs
Phys. Rev. Lett. 124, 166404 (2020)
Photocurrent-driven transient symmetry breaking in the Weyl semimetal
Nature Materials 21, 62–66 (2021).
M. Z. Hasan, In Proceedings Volume PC12419, SPIE; Ultrafast Phenomena and Nanophotonics XXVII (2023)
Fermi arc, correlations & Superconductivity
Coexistence of Bulk-Nodal and Surface-Nodeless Cooper Pairings in a Superconducting Topological Semimetal.
Phys. Rev. Lett. 130, 046402 (2023).
Phys. Rev. Lett. 130, 066402 (2023)
Tunable topologically driven Fermi arc van Hove singularities.
Nature Physics 19, 682 (2023).
Quantum Phase Transitions
Unconventional Scaling of the Superfluid Density with the Critical Temperature in Transition Metal Dichalcogenides
Science Adv. 5, eaav8465 (2019)
Quantum Phase Transition of Correlated Iron-Based Superconductivity in LiFe1- xCoxAs
Phys. Rev. Lett. 123, 217004 (2019)
Artificial Condensed Matter Lattice
“A novel artificial condensed matter lattice and a new platform for one-dimensional topological phases”
Science Adv. 3 e1501692 (2017)
Nematic-Order & Quantum Control
Nematic-Order & Quantum Control: "Giant and anisotropic many-body spin–orbit tunability in a correlated kagome magnet,"
Nature 562, 91–95 (2018).
Nature 612, 647-657 (2022). (review)
Knotted Quantum Matter
Knotted Quantum Matter: Observation of a linked-loop quantum state in a topological magnet
Science 365, 1278-1281 (2019)
Nature(Link is external) 604, 647–652 (2022)
Topological Quantum Science and Engineering:
Topological Quantum Science and Engineering: Hasan lab helped launch the field of Topological Insulators by directly detecting the novel surface states and thoroughly demonstrating their unusual topological properties using advanced spin-sensitive spectroscopic techniques (50,000+ citations). Subsequently, Hasan group has theoretically and experimentally discovered many novel classes of topological matter and topological phase transitions including Topological Magnets (via the demonstration of Chern gap in 2012) using novel instrumentations and innovative methods and introduced designed discovery methods. The field expanded to include topological semimetals, notably Weyl Semimetals, whose states mimic massless fermions considered in quantum field theory. In 2015 Hasan group observed the emergent Weyl fermions and novel topological Fermi arc surface states in several topological semimetals he and his team theoretically predicted in arsenide and other materials. His Weyl fermion work is based on his and his team's theoretical predictions in several spin-orbit materials. Subsequently, he has theoretically and experimentally discovered many novel classes of magnetic topological semimetals. He has also made groundbreaking contributions (theoretical and experimental) in the subfields of topological phase transitions, topological magnets in 2D and 3D, topological nodal-line and drumhead metals, topological magnetic semimetals, topological chiral crystals, topological Hopf link semimetals, topological superconductors, Helicoid-arc quantum states and Kagome magnets and materials, Chern magnets and charge-ordered Kagome superconductors enabled by innovative applications and development of experimental methods. He identified room temperature topological materials. A vast majority of his experimental discoveries are based on his and his team's theoretical predictions of topological materials. These materials are broadly important for future device applications with higher energy efficiency, as quantum information science platforms, and for exploring new emergent or many-body quantum physics. He has also contributed to the conceptual design and theoretical development of some of these topics and written several comprehensive review articles by invitation. The methodologies introduced by him to explore and discover topological materials and phenomena are being used by others world-wide to further advance the field and led to new discoveries. His experiments and methods have been seminal in giving rise to the field of "Topological Quantum Matter" with more than 100,000 citations (over 250 publications with h-factor 105+), which is now growing vigorously at the nexus of condensed matter physics, materials engineering, nano-science, device physics & quantum engineering, chemistry and relativistic quantum field theory as evidenced in all citation tracks.
Source:
Strongly correlated electron physics: Quantum many-body physics
(Work at Hasan Lab) Quantum many-body physics in doped Mott insulators, Charge-order and Superconductivity competition, Nematic order & fluctuations etc.
Hasan et.al., Phys. Rev. Lett. 92, 246402 (2004); Phys. Rev. Lett. 96, 046407 (2006); Phys. Rev. Lett. 97, 186405 (2006); Phys. Rev. Lett. 96, 216405 (2006). Phys. Rev. Lett. 98, 117007 (2007) and Phys. Rev. Lett. 99, 167002 (2007). Phys. Rev. B 78, 184508 (2008); Phys. Rev. Lett. 103, 037002 (2009). Nature’18, NaturePhys’19, PRL’19, PRL’20, NatureCom’20a, NatureCom’20b, NatureCom’20c, Nature’20, NatureMat’21, PRL’21, Science’19, Nature’19, Nature’22a, Nature’22b, PRL’22, NaturePhys’22, NatureCom’22, NatureCom’23a, NatureCom’23b, NaturePhys’23, NatureCom’24a, NatureCom’24b, NatureCom’24c, NatureMat’24
A New State of Matter ...
Intrinsic fully bulk INSULATING 3D-Topo-Insulators (Nature Physics 2014)
Intrinsic fully bulk INSULATING 3D-Topo-Insulators (Nature Physics 2014)
https://online.kitp.ucsb.edu/online/lsmatter_c15/hasan/oh/17.html
Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class (Bi2Se3 class) with spin-polarized single-Dirac-cone on the surface
Theoretical Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class (Bi2Se3 class) with spin-polarized single-Dirac-cone on the surface
https://arxiv.org/abs/0908.3513
Intrinsic fully bulk INSULATING 3D-Topo-Insulators (Nature Physics 2014)
https://online.kitp.ucsb.edu/online/lsmatter_c15/hasan/oh/17.html
https://arxiv.org/abs/0908.3513 (2009) [Submitted to Nature Phys in 2008 ]
APS-Physics: "Topological Invariants via Spectroscopy (New Methods)
APS-Physics: "Topological Invariants via Spectroscopy (New Methods)
Topo Invariants precisely define a New Topo State of Matter which can be precisely measured via Spectroscopic measurements (no transport or quantum Hall transport is needed). This invited talk at APS-Physics elaborates this NEW method which enabled discovery of many novel topological states of matter…
Recent results ...
KITP Lecture link .. https://www.on.kitp.ucsb.edu/online/lowdim09/hasan/oh/01.html
KITP Lecture link ..
https://www.on.kitp.ucsb.edu/online/lowdim09/hasan/oh/01.html
Unexpected and unpredicted novel (many-body, correlated) quantum phenomena in Topological Kagome Magnets & Superconductors:
Unexpected and unpredicted novel (many-body, correlated) quantum phenomena in Topological Kagome Magnets & Superconductors:
Experiments started in 2017, completed in 2017, Nature’18, NaturePhys’19, PRL’19, PRL’20, NatureCom’20a, NatureCom’20b, NatureCom’20c, Nature’20, NatureMat’21, PRL’21, Science’19, Nature’19, Nature’22a, Nature’22b, PRL’22, NaturePhys’22, NatureCom’22, NatureCom’23a, NatureCom’23b, NaturePhys’23, NatureCom’24a, NatureCom’24b, NatureCom’24c, NatureMat’24
Novel quantum phenomena in Topological kagome magnets and superconductors : https://www.nature.com/articles/s41586-022-05516-0
A New Paradigm : A Novel Method (Rev. of Mod. Phys. 82, 3045, 2010) for decisively measuring "Topological Invariants"
A New Paradigm : A Novel Method (Rev. of Mod. Phys. 82, 3045, 2010) for decisively measuring "Topological Invariants"
A New Paradigm : A Novel Method (see, invited review, RMP 82, 3045, 2010) for decisively measuring "topological invariants" which led to the creation of a new continent of research (the field of topological materials) with multiple groundbreaking discoveries, including topo. Dirac-Weyl fermions, Fermi arc and more..
https://journals.aps.org/rmp/abstract/10.1103/RevModPhys.82.3045
Theoretical Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class (Bi2Se3 class) with spin-polarized single-Dirac-cone on the surface
Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class (Bi2Se3 class) with spin-polarized single-Dirac-cone on the surface
https://arxiv.org/abs/0908.3513
Theoretical Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class (Bi2Se3 class) with spin-polarized single-Dirac-cone on the surface
Intrinsic fully bulk INSULATING 3D-Topo-Insulators (Nature Physics 2014)
https://online.kitp.ucsb.edu/online/lsmatter_c15/hasan/oh/17.html
New Methods ...
