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  Welcome to the Hasan Research Group website! Our lab is focused on the search and discovery of novel quantum phases of matter. Currently, we grow and control properties of quantum materials, perform first-principle theoretical calculations/predictions and develop advanced spectroscopic techniques and related tools that provide new insights into the emergent behavior of matter. We invite you to visit our labs (Laboratory for Topo. Quantum Matter and Spectroscopy: B7-B2-B9-B60 Jadwin Hall) in the dept of physics at Princeton.
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  Lab Theme: QFT, Topology & Emergence in the Condensed Matter Universe
Why are there analogies between cond.matter and particle theory?
Topological Phases of Matter
Reading List (click here)

U.S. Dept of Energy support (DOE physicists at work)
PNAS Front Matter homepage (September, 2016): Topological Insulators
Proc. of National Academy of Sciences USA
PhysicsWorld (U.K.) homepage (August, 2016): Topological Insulators (100sec Science Series)
Physics Today: "Search & Discovery" News on Topological Insulators
PhysicsWorld (February, 2011); Physics Today (January, 2010)
Physics Today (U.S.A.) Quantum Materials: New funding for Quantum Systems (2013)
PhysicsWorld News (July, 2015) Weyl fermion semimetals & Fermi arcs
PhysicsWorld (March, 2016) Weyl fermion semimetals & Topo. Nodal Fermion Semimetals
Discovery of Weyl Fermions, Topological Fermi Arcs and Topological Nodal-Line States of Matter
(Key Developments in Physics: 2Physics, 2015)

PhysicsWorld (2016)


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Recent Publications :

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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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A strongly robust type II topological Weyl fermion semimetal state in Ta3S2

Guoqing Chang, Su-Yang Xu, Daniel S. Sanchez, Shin-Ming Huang, Chi-Cheng Lee, Tay-Rong Chang, Guang Bian, Hao Zheng, Ilya Belopolski, Nasser Alidoust, Horng-Tay Jeng, Arun Bansil, Hsin Lin, and M. Zahid Hasan
Science Adv. e1600295 (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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  Discovery of Weyl fermion semimetals 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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Atomic Scale Visualization of Quantum Interference on a Weyl Semimetal Surface by Scanning Tunneling Microscopy/Spectroscopy

H. Zheng, S.-Y. Xu, G. Bian, C. Guo, G. Chang, D. S. Sanchez, I. Belopolski, C.-C. Lee, S.-M. Huang, X. Zhang, R. Sankar, N. Alidoust, T.-R. Chang, F. Wu, T. Neupert, F. Chou, H.-T. Jeng, N. Yao, A. Bansil, S. Jia, H. Lin, M. Z. Hasan
ACS Nano 10, 1378 (2016, submitted Oct 2015)

 
 

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New funding for quantum systems

 
 
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Engineering electronic structure of a 2D topological insulator Bi(111) bilayer on Sb nanofilms by quantum confinement effect

G. Bian, Z. F. Wang, X. Wang, C. Xu, S.-Y. Xu, T. Miller, M. Z. Hasan, F. Liu, and T.-C. Chiang
ACS Nano 10, 3859 (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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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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Prediction of an 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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Unconventional transformation of spin Dirac phase across a topological quantum phase transition
S.-Y. Xu, M. Neupane, I. Belopolski et al. Nat. Commun. 6:6870 (2015)

 
 
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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Pump-Probe Ultrafast Spectroscopy

 
  Gigantic surface life-time of an intrinsic topological insulator revealed via time-resolved (pump-probe) ARPES
M. Neupane, S.-Y. Xu, Y. Ishida, S. Jia, B. M. Fregoso, C. Liu, I. Belopolski, G. Bian, N. Alidoust, T. Durakiewicz,
V. Galitski, S. Shin, R. J. Cava, and M. Z. Hasan
Phys. Rev. Lett. 115, 116801 (2015)

 
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Discovery of Weyl Fermion Semimetals: TaAs, NbAs, NbP, TaP, SrSi2, Ta3S2, LaAlGe
 
 
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)

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
Phys. Rev. B (2016)

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
Phys. Rev. B (2016)

A strongly robust type-II 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
Science Advances (2016)

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

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


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  Topological Weyl Semimetal and Topological Fermi Arcs  
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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).

 
Topological Semimetal (Double Weyl Semimetal)
 
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Observation of Fermi Arc Surface States in a Topological Metal.
Published in S.-Y. Xu, C. Liu, S. Kushwaha, et al., Science 347, 294 (2015).

 
2D Topological Superconductor based on Topological Insulators
 
  NbSe2  
 
Spin and angle resolved photoemission (spin-ARPES) measurements on Bi2Se3/NbSe2 heterostructure demonstrate topological superconductivity and helical Cooper pairing via proximity effect.
Published in S.-Y. Xu, N. Alidoust, I. Belopolski et al., Nature Physics 10, 943 (2014).

 
  NbSe2  
 
Observation of topological surface state quantum Hall effect in an intrinsic three-dimensional topological insulator.
Published in Y. Xu, I. Miotkowski, C. Liu, J. Tian, H. Nam, N. Alidoust, J. Hu, C.-K. Shih, M. Z. Hasan and Y. P. Chen,
Nature Physics 10, 956 (2014).

 
  NbSe2  
 
Observation of a three-dimensional topological Dirac semimetal phase in high-mobility Cd3As2.
Published in M. Neupane, S.-Y. Xu, R. Sankar, et al., Nature Commun. 5, 3786 (2014).

 
  CeB6  
 
Observation of quantum-tunnelling-modulated spin texture in ultrathin topological insulator Bi2Se3 films.
Published in M. Neupane, A. Richardella, J. Sanchez-Barriga, et al., Nature Commun. 5, 3841 (2014).

 
  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)

 
  TKI  
  TKI1  
 
First spectroscopic observation of topological surface states in a topological Kondo insulator SmB6.
Published in M. Neupane, N. Alidoust, S.-Y. Xu, et al., Nature Commun. 4, 2991 (2013).

 
  MoS21  
 
Magnetic Topological Insulators: Hedgehog spin texture and Berry's phase tuning in a magnetic topological insulator
Published in S.-Y. Xu, M. Neupane, C. Liu, et al.,
Nature Physics 8, 616 (2012).

 
  wray2008
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Observation of a topological crystalline insulator phase and topological phase transition in Pb1-xSnxTe
Published in Su-Yang Xu, Chang Liu, N. Alidoust, et al.,
Nature Commun. 3, 1192 (2012)

 
  NbSe2  

Half-Heusler ternary compounds as new multifunctional experimental platforms for topological quantum phenomena.
Published in H. Lin, L. A. Wray, Y. Xia, et al., Nature Materials 9, 546 (2010).

  NbSe2  

Observation of topological order in a superconducting doped topological insulator.
Published in L. A. Wray, S.-Y. Xu, Y. Xia, et al., Nature Physics 6, 855 (2010).

  TQPT  
 
Topological Phase Transition and Texture Inversion in a Tunable Topological Insulator.
S.-Y. Xu, Y. Xia, L. A. Wray et al.;
Science 332, 560 (2011)

 
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A tunable topological insulator in the spin helical Dirac transport regime.
D. Hsieh, D. Qian, Y. Xia, et al.;
Nature 460, 1101 (2009)

 
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Berry's phase and quantization in topological insulators.
M. Zahid Hasan
Physics 3, 62 (2010)


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  TI1  
 
The first 3D topological insulator: Bi1-xSbx

D. Hsieh, D. Qian, Y. Xia, et al., Nature 452, 970 (2008)
D. Hsieh, Y. Xia, L. A. Wray, et al., Science 323, 919 (2009)


 
  NbSe2  
  NbSe2  
  Demonstration of a Fully Bulk Insulating (Intrinsic) Topological Insulator
 
 
Observation of topological surface state quantum Hall effect in an intrinsic three-dimensional topological insulator.
Published in Y. Xu, I. Miotkowski, C. Liu, J. Tian, H. Nam, N. Alidoust, J. Hu, C.-K. Shih, M. Z. Hasan and Y. P. Chen,
Nature Physics 10, 956 (2014).