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Weyl Fermion Semimetals and Topology

Some examples of our theoretical predictions can be found here

Topo Insulators to Weyl Fermions (NATURE News, July, 2017)

PhysicsWorld News: "Weyl fermions are spotted at long last" (July, 2015)

Berkeley Lab News on Weyl Fermions

PhysicsWorld (2016)


"(Theoretical prediction) New type of Weyl semimetal with quadratic double Weyl fermions"


Opening Science Talk (Physics-Next, APS-Physics):
Quantum Fields to Condensed Matter: New Topological Phases of Matter in Natural and Artificial Materials

Keynote Talk at Hubbard theory consortium summer school (London) "Topo.Order in Real Materials"

Mott Lecture Series in Physics

Moore foundation Symposium talk : "Theoretical and experimental discovery of Weyl fermion, topological nodal-line fermion and Chiral anomaly materials and the new physics frontier"


American Physical Society Talk:
"Discovery (Theoretical and Experimental) of Weyl fermion semimetal and topological Fermi arc quasiparticles in TaAs, NbAs, NbP, TaP and related materials"

New Topological States of Matter: Platform for emergent Dirac, Majorana & Weyl fermions (CalTech)


NSF New Frontiers Workshop Talk:
"Theoretical & experimental discovery of Weyl, topo. nodal line & chiral anomaly materials"


PhysicsWorld multimedia interview: "What is a Topological Metal? (2016)

Princeton theory center (PCTS) talk : "Theoretical and experimental discovery of Weyl fermion, topological nodal-line fermion and Chiral anomaly materials and the new physics frontier"


"Discovery (theoretical and experimental) of Lorentz-invariant and Lorentz-violating emergent Weyl fermions in topological materials (TaAs class & LaAlGe class)"
MIT Chez Pierre Seminar in Condensed Matter Physics

Lecture Link

"Theoretical and experimental discovery of Weyl fermion, topological nodal-line fermion and Chiral anomaly materials and the new physics frontier" (Rutgers 2016)

Physics Colloquium: "Discovery of Weyl fermions and topological Fermi arcs"
Kavli KITP talk on Weyl fermions in electronic crystals
Inst. for Adv. Study Distinguished Lecture at HKUST on New Topological States of Matter

Topological electronic structure and Weyl semimetal in the TlBiSe2 class of semiconductors
B. Singh, A. Sharma, H. Lin, M. Z. Hasan, R. Prasad, and A. Bansil
Physical Review B 86, 115208 (2012)
(Theoretical Prediction) A Weyl Fermion semimetal with surface Fermi arcs in the TaAs class
S.-M. Huang, S.-Y. Xu, I. Belopolski, C.-C. Lee, G. Chang, B. Wang, N. Alidoust, G. Bian, M. Neupane, C. Zhang, S. Jia, A. Bansil, H. Lin, and M. Z. Hasan
Nature Commun. 6:7373 (2015, submitted Nov 2014)


 
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  Discovery of Weyl fermion named a 'breakthrough of the year' by Physics World
PhysicsWorld News: "Weyl fermions are spotted at long last"
News at Lawrence Berkeley National Laboratory (LBNL), MIT physics news
Physics Highlights of the Year 2015 (Physics - American Physical Society)
 
 

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(Topological Semimetals) Weyl semimetals, Fermi arcs and chiral anomaly

S. Jia, S.-Y. Xu, M. Z. Hasan
Nature Materials 15, 1140-1144 (2016) (Cover Image & Story)
 
 
Topological Weyl Semimetal and Topological Fermi Arcs
 
 

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Signatures of the Adler-Bell-Jackiw chiral anomaly in a Weyl semimetal

C. Zhang, S.-Y. Xu, I. Belopolski, Z. Yuan, Z. Lin, B. Tong, N. Alidoust, C.-C. Lee, S.-M. Huang, H. Lin, M. Neupane, D. S. Sanchez, H. Zheng, G. Bian, J. Wang, C. Zhang, T. Neupert, M. Z. Hasan, S. Jia
Nature Communications 7:10735 (2016)

 
 

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  Spin polarization and texture of the Fermi arcs in the Weyl Fermion semimetal TaAs
S.-Y. Xu, I. Belopolski, D. S. Sanchez, M. Neupane, G. Chang, K. Yaji, Z. Yuan, C. Zhang, K. Kuroda, G. Bian, C. Guo, H. Lu, Y. Feng, T.-R. Chang, N. Alidoust, H. Zheng, C.-C. Lee, S.-M. Huang, C.-H. Hsu, Horng-Tay Jeng, A. Bansil, A. Alexandradinata, T. Neupert, T. Kondo, S. Shin, H. Lin, S. Jia, M Z. Hasan
Phys. Rev. Lett. 116, 096801 (2016)

 
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New type of Weyl semimetal with quadratic double Weyl fermions in SrSi2
S.-M. Huang, S.-Y. Xu, I. Belopolski et al., PNAS 113, 1180 (2015)

 
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Criteria for Directly Detecting Topological Fermi Arcs in Weyl Semimetals
I. Belopolski, S.-Y. Xu, D. S. Sanchez et al. Phys. Rev. Lett. 116, 066802 (2016)

 
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Signatures of Fermi Arcs in the Quasiparticle Interferences of the Weyl Semimetals TaAs and NbP
G. Chang, S.-Y. Xu, H. Zheng et al., Phys. Rev. Lett. 116, 066601 (2016)

 
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Discovery of a Weyl Fermion semimetal and topological Fermi arcs.
Published in S.-Y. Xu, I. Belopolski, N. Alidoust, et al., Science 349, 613 (2015).

 
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A Weyl Fermion semimetal with surface Fermi arcs in the transition metal monopnictide TaAs class.
Published in S.-M. Huang, S.-Y. Xu, I. Belopolski, et al., Nature Commun. 6:7373 (2015).

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Discovery of a Weyl fermion state with Fermi arcs in niobium arsenide.
Published in S.-Y. Xu, N. Alidoust, I. Belopolski, et al., Nature Physics 11, 748 (2015).

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Experimental discovery of a topological Weyl semimetal state in TaP.
Published in S.-Y. Xu, I. Belopolski, D. S. Sanchezet al., Science Advances 1, 1501092 (2015).

 
Discovery of Weyl Fermion Semimetals: TaAs, NbAs, NbP, TaP, SrSi2
 
 
Topological electronic structure and Weyl semimetal in the TlBiSe2 class of semiconductors.
B. Singh, A.h Sharma, H. Lin, M. Z. Hasan, R. Prasad, and A. Bansil
Physical Review B 86, 115208 (2012)

Theoretical Prediction: A Weyl Fermion semimetal with surface Fermi arcs in the transition metal monopnictide TaAs class
S.-M. Huang, S.-Y. Xu, I. Belopolski, C.-C. Lee, G. Chang, B. Wang, N. Alidoust, G. Bian, M. Neupane, C. Zhang, S. Jia, A. Bansil, H. Lin, M. Z. Hasan
Nature Commun. 6:7373 (2015) (submitted Nov 2014)
Also see: Phys. Rev. X 5, 011029 (2015) (submitted Jan 2015)

Experimental Discovery: Discovery of a Weyl Fermion semimetal and topological Fermi arcs
S.-Y. Xu, I. Belopolski, N. Alidoust, M. Neupane, G. Bian, C. Zhang, R. Sankar, G. Chang, Z. Yuan, C.-C. Lee, S.-M. Huang, H. Zheng, J. Ma, D. S. Sanchez, B. Wang, A. Bansil, F. Chou, P. P. Shibayev, H. Lin, S. Jia, and M. Z. Hasan
Science 349, 613 (2015) (submitted Feb. 2015)

PhysicsWorld News: "Weyl fermions are spotted at long last"

APS-Physics (American Physical Society): "Weyl Fermions"

Science News: "Elusive particle shows up in semimetal"

Nature Materials News: "Weyl fermions: Massless yet real"

Nature Physics News: "After a Weyl"

ChemistryWorld News: "Elusive fermion found at long last"

Physics (American Physical Society): "Where the Weyl Things Are"

Discovery of a Weyl Fermion state with Fermi arcs in niobium arsenide
S.-Y. Xu, N. Alidoust, I. Belopolski, Z. Yuan, G. Bian, T.-R. Chang, H. Zheng, V. Strocov, D. S. Sanchez, G. Chang, C. Zhang, D. Mou, Y. Wu, L. Huang, C.-C. Lee, S.-M. Huang, B. Wang, A. Bansil, H.-T. Jeng, T. Neupert, A. Kaminski, H. Lin, S. Jia, and M. Z. Hasan
Nature Physics 11, 748 (2015)

NaturePhysics: "Discovery of a Weyl Fermion state"

Nature Physics News: "After a Weyl"

Experimental discovery of a topological Weyl semimetal state in TaP
S.-Y. Xu, I. Belopolski, D. S. Sanchez, C. Guo, G. Chang, C. Zhang, G. Bian, Z. Yuan, H. Lu, Yi. Feng, T.-R. Chang, P. P. Shibayev, M. L. Prokopovych, N. Alidoust, H. Zheng, C.-C. Lee, S.-M. Huang, R. Sankar, F. Chou, C.-H. Hsu, H.-T. Jeng, A, Bansil, T. Neupert, V. N. Strocov, H. Lin, S. Jia, M. Z. Hasan
Science Advances 1, 1501092 (2015)

Fermi arc topology and interconnectivity in Weyl fermion semimetals TaAs, TaP, NbAs, and NbP
C.-C. Lee, S.-Y. Xu, S.-M. Huang, D. S. Sanchez, I. Belopolski, G. Chang, G. Bian, N. Alidoust, H. Zheng, M. Neupane,B. Wang, A. Bansil, M. Z. Hasan, and H. Lin
Phys. Rev. B 92, 235104 (2015)

Signatures of Fermi Arcs in the Quasiparticle Interferences of the Weyl Semimetals TaAs and NbP
G. Chang, S.-Y. Xu, H. Zheng, C.-C. Lee, S.-M. Huang, I. Belopolski, D. S. Sanchez, G. Bian, N. Alidoust, T.-R. Chang, C.-H. Hsu, H.-T. Jeng, A. Bansil, H. Lin, M. Z. Hasan
Phys. Rev. Lett. 116, 066601 (2016)

Criteria for Directly Detecting Topological Fermi Arcs in Weyl Semimetals
I. Belopolski, S.-Y. Xu, D. S. Sanchez, G. Chang, C. Guo, M. Neupane, H. Zheng, C.-C. Lee, S.-M. Huang, G. Bian, N. Alidoust, T.-R. Chang, B. Wang, X. Zhang, A. Bansil, H.-T. Jeng, H. Lin, S. Jia, M. Z. Hasan
Phys. Rev. Lett. 116, 066802 (2016)

New type of Weyl semimetal with quadratic double Weyl fermions
S.-M. Huang, S.-Y. Xu, I. Belopolski, C.-C. Lee, G. Chang, B. Wang, N. Alidoust, M. Neupane, H. Zheng, D. Sanchez, A. Bansil, G. Bian, H. Lin, and M. Z. Hasan
PNAS 113, 1180 (2015)

Prediction of an arc-tunable Weyl Fermion metallic state in MoxW1-xTe2
T.-R. Chang, S.-Y. Xu, G. Chang, C.-C. Lee, S.-M. Huang, B. Wang, G. Bian, H. Zheng, D. S. Sanchez, I. Belopolski, N. Alidoust, M. Neupane, A. Bansil, H.-T. Jeng, H. Lin, M. Zahid Hasan
Nature Commun. 7:10639 (2016)

Signatures of the Adler-Bell-Jackiw chiral anomaly in a Weyl semimetal
C. Zhang, S.-Y. Xu, I. Belopolski, Z. Yuan, Z. Lin, B. Tong, N. Alidoust, C.-C. Lee, S.-M. Huang, H. Lin, M. Neupane, D. S. Sanchez, H. Zheng, G. Bian, J. Wang, C. Zhang, T. Neupert, M. Z. Hasan, S. Jia
Nature Commun. 7:10735 (2016)

Spin polarization and texture of the Fermi arcs in the Weyl Fermion semimetal TaAs
S.-Y. Xu, I. Belopolski, D. S. Sanchez, M. Neupane, G. Chang, K. Yaji, Z. Yuan, C. Zhang, K. Kuroda, G. Bian, C. Guo, H. Lu, Y. Feng, T.-R. Chang, N. Alidoust, H. Zheng, C.-C. Lee, S.-M. Huang, C.-H. Hsu, Horng-Tay Jeng, A. Bansil, A. Alexandradinata, T. Neupert, T. Kondo, S. Shin, H. Lin, S. Jia, M Z. Hasan
Phys. Rev. Lett. 116, 096801 (2016)

Quantum Phase Transitions in Weyl Semimetal Tantalum Monophosphide
C. Zhang, Z. Lin, C. Guo, S.-Y. Xu, C.-C. Lee, H. Lu, S.-M. Huang, G. Chang, C.-H. Hsu, H. Lin, L. Li, C. Zhang, T. Neupert, M. Z. Hasan, J, Wang, S. Jia
arXiv:1507.06301 (2015)

Unoccupied electronic structure and signatures of topological Fermi arcs in the Weyl semimetal candidate MoxW1-xTe2
I. Belopolski, S.-Y. Xu, Y. Ishida, X. Pan, P. Yu, D. S. Sanchez, M. Neupane, N. Alidoust, G. Chang, T.-R. Chang, Y. Wu, G. Bian, H. Zheng, S.-M. Huang, C.-C. Lee, D. Mou, L. Huang, Y. Song, B. Wang, G. Wang, Y.-W. Yeh, N. Yao, J. Rault, P. Lefevre, F. Bertran, H.-T. Jeng, T. Kondo, A. Kaminski, H. Lin, Z. Liu, F. Song, S. Shin, M. Z. Hasan
arXiv:1512.09099

A strongly robust Weyl fermion semimetal state in Ta3S2
G. Chang, S.-Y. Xu, D. S. Sanchez, S.-M. Huang, C.-C. Lee, T.-R. Chang, H. Zheng, G. Bian, I. Belopolski, N. Alidoust, H.-T. Jeng, A. Bansil, H. Lin, M. Z. Hasan
arXiv:1512.08781

Magnetic and noncentrosymmetric Weyl fermion semimetals in the RAlX family of compounds (R=rare earth, Al=aluminium, X=Si, Ge)
G. Chang, B. Singh, S.-Y. Xu, G. Bian, S.-M. Huang, C.-H. Hsu, I. Belopolski, N. Alidoust, D. S. Sanchez, H. Zheng, H. Lu, X. Zhang, Y. Bian, T.-R. Chang, H.-T. Jeng, A. Bansil, H. Hsu, S.g Jia, T.s Neupert, H. Lin, M. Z. Hasan
arXiv:1604.02124

Observation of Topological Nodal Fermion Semimetal Phase in ZrSiS
M. Neupane, I. Belopolski, M. M. Hosen, D. S. Sanchez, R. Sankar, M. Szlawska, S.-Y. Xu, K. Dimitri, N. Dhakal, P. Maldonado, P. M. Oppeneer, D. Kaczorowski, F. Chou, M. Z. Hasan, T. Durakiewicz
arXiv:1604.00720

Discovery of Lorentz-violating Weyl fermion semimetal state in LaAlGe materials
S.-Y. Xu, N. Alidoust, G. Chang, H. Lu, B. Singh, I. Belopolski, D. Sanchez, X. Zhang, G. Bian, H. Zheng, M.-A. Husanu, Y. Bian, S.-M. Huang, C.-H. Hsu, T.-R. Chang, H.-T. Jeng, A. Bansil, V. N. Strocov, H. Lin, S. Jia, M. Z. Hasan
arXiv:1603.07318

Room-temperature magnetic topological semimetal state in half-metallic Heusler Co2TiX (X=Si, Ge, or Sn)
G. Chang, S.-Y. Xu, H. Zheng, B. Singh, C.-H. Hsu, I. Belopolski, D. S. Sanchez, G. Bian, N. Alidoust, H. Lin, M. Z. Hasan
arXiv:1603.01255

Unoccupied electronic structure and signatures of topological Fermi arcs in the Weyl semimetal candidate MoxW1-xTe2
I. Belopolski, S.-Y. Xu, Y. Ishida, X. Pan, P. Yu, D. S. Sanchez, M. Neupane, N. Alidoust, G. Chang, T.-R. Chang, Y. Wu, G. Bian, H. Zheng, S.-M. Huang, C.-C. Lee, D. Mou, L. Huang, Y. Song, B. Wang, G. Wang, Y.-W. Yeh, N. Yao, J. Rault, P. Lefevre, F. Bertran, H.-T. Jeng, T. Kondo, A. Kaminski, H. Lin, Z. Liu, F. Song, S. Shin, M. Z. Hasan
arXiv:1512.09099

 
 
Topological Nodal-line Fermions
 
 
Topological Nodal-Line Fermions in Spin-Orbit Metal PbTaSe2

G. Bian, T.-R. Chang, R. Sankar, S.-Y. Xu, H. Zheng, T. Neupert, C.-K. Chiu, S.-M. Huang, G. Chang, I. Belopolski, D. S. Sanchez, M. Neupane, N. Alidoust, C. Liu, B. Wang, H.-T. Jeng, A. Bansil, F. Chou, H. Lin, and M. Z. Hasan
Nature Commun. 7:10556 (2016, submitted Nov 2015)
 
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  Drumhead Surface States and Topological Nodal-Line Fermions in TlTaSe2
G. Bian.,T.-R. Chang., H. Zheng, S. Velury, S.-Y. Xu, T. Neupert, C.-K. Chiu, D. S. Sanchez, I. Belopolski, N. Alidoust, P.-J. Chen, G. Chang, A. Bansil, H.-T. Jeng, H. Lin, and M. Z. Hasan
arXiv:1508.07521

 
 
Some examples of our theoretical predictions

 
  MoS21  
 
Observation of monolayer valence band spin-orbit effect and induced quantum well states in MoX2
Published in Nasser Alidoust, Guang Bian, Su-Yang Xu, et al.,
Nature Commun. 5, 4673 (2014)

 
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A Weyl Fermion semimetal with surface Fermi arcs in the transition metal monopnictide TaAs class.
Published in S.-M. Huang, S.-Y. Xu, I. Belopolski, et al., Nature Commun. 6:7373 (2015).

 
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Drumhead Surface States and Topological Nodal-Line Fermions in TlTaSe2.
G. Bian.,T.-R. Chang., H. Zheng, et al., Phys. Rev. B 93, 121113(R) (2016).

 
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A strongly robust Weyl fermion semimetal state in TaS.
G. Chang, S.-Y. Xu, D. S. Sanchez, et al., arXiv:1512.08781 (2015).

 
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Arc-tunable Weyl Fermion metallic state in MoxW1-xTe2.
T.-R. Chang, S.-Y. Xu, G. Chang, et al., Nature Commun. 7:10639 (2016)

 
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Signatures of Fermi Arcs in the Quasiparticle Interferences of the Weyl Semimetals TaAs and NbP
G. Chang, S.-Y. Xu, H. Zheng et al., Phys. Rev. Lett. 116, 066601 (2016)

 
  DS
DS
 
A new type of Weyl semimetal with quadratic double Weyl fermions in SrSi2
S.-M. Huang, S.-Y. Xu, I. Belopolski et al., PNAS 113, 1180 (2015)

 
  DS  
Criteria for Directly Detecting Topological Fermi Arcs in Weyl Semimetals
I. Belopolski, S.-Y. Xu, D. S. Sanchez et al. Phys. Rev. Lett. 116, 066802 (2016)

 
  DS
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Magnetic and noncentrosymmetric Weyl fermion semimetals in the RAlX family of compounds (R=rare earth, Al=aluminium, X=Si, Ge).
G. Chang, B. Singh, S.-Y. Xu, et al., arXiv:1604.02124

 
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Room-temperature magnetic topological semimetal state in half-metallic Heusler Co2TiX (X=Si, Ge, or Sn).
G. Chang, S.-Y. Xu, H. Zheng, et al., arXiv:1603.01255

 
 

Type-II Weyl fermions (Theoretical Prediction in LaGeAl and Experimental Discovery)


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"Discovery of Lorentz violating type-II Weyl fermions in LaGeAl "
Suyang Xu, N. Alidoust, I. Belopolski et.al.,
Science Advances 3, e1603266 (2017)
 
 
H. Weyl had a Princeton address in his fermion paper (Z. Phys. 56, 330 (1929))!

STM/STS Image of a Weyl semimetal surface:
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H. Weyl had a Princeton address in his fermion paper (Z. Phys. 56, 330 (1929))!

STM/STS Image of a Weyl semimetal surface:
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Tilted Weyl cone in topological materials bears an analogy to the lightcone bending near blackholes (simulated Lorentz violation in quantum matter).
Science Advances (2017)