Topological origin of the type-II Dirac fermions in PtSe2

DOI: 10.1103/PhysRevMaterials.1.074202

Authors: Yiwei Li (University of Oxford) , Yunyouyou Xia (ShanghaiTech University and CAS-Shanghai Science Research Center) , Sandy Adhitia Ekahana (University of Oxford) , Nitesh Kumar (Max Planck Institute for Chemical Physics of Solids) , Juan Jiang (ShanghaiTech University and CAS-Shanghai Science Research Center; Advanced Light Source) , Lexian Yang (Tsinghua University) , Cheng Chen (University of Oxford) , Chaoxing Liu (Pennsylvania State University) , Binghai Yan (Max Planck Institute for Chemical Physics of Solids) , Claudia Felser (Max Planck Institute for Chemical Physics of Solids) , Gang Li (ShanghaiTech University and CAS-Shanghai Science Research Center) , Zhongkai Liu (ShanghaiTech University and CAS-Shanghai Science Research Center) , Yulin Chen (University of Oxford; ShanghaiTech University and CAS-Shanghai Science Research Center; Tsinghua University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physical Review Materials , VOL 1

State: Published (Approved)
Published: December 2017
Diamond Proposal Number(s): 15364

Abstract: Group VIII transition-metal dichalcogenides have recently been proposed to host type-II Dirac fermions. They are Lorentz-violating quasiparticles marked by a strongly tilted conic dispersion along a certain momentum direction and therefore have no analogs in the standard model. Using high-resolution angle-resolved photoemission spectroscopy, we systematically studied the electronic structure of PtSe2 in the full three-dimensional Brillouin zone. As predicted, a pair of type-II Dirac crossings is experimentally confirmed along the kz axis. Interestingly, we observed conic surface states around time-reversal-invariant momenta ¯¯¯ Γ and ¯¯¯¯ M points. The signatures of nontrivial topology are confirmed by the first-principles calculation, which shows an intricate parity inversion of bulk states. Our discoveries not only contribute to a better understanding of topological band structure in PtSe2 but also help further explore the exotic properties, as well as potential application, of group VIII transition-metal dichalcogenides.

Journal Keywords: Electronic structure; Fermi surface; Quasiparticles; Surface states; Topological phases of matter

Subject Areas: Materials, Physics


Instruments: I05-ARPES

Added On: 10/01/2018 12:15

Discipline Tags:

Quantum Materials Physics Hard condensed matter - structures Materials Science

Technical Tags:

Spectroscopy Angle Resolved Photoemission Spectroscopy (ARPES)