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Phys Rev Lett. 2018 Nov 2;121(18):186401. doi: 10.1103/PhysRevLett.121.186401.

Experimental Observation of Hidden Berry Curvature in Inversion-Symmetric Bulk 2H-WSe_{2}.

Author information

1
Institute of Physics and Applied Physics, Yonsei University, Seoul 03722, Korea.
2
Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea.
3
Department of Chemistry, Pohang University of Science and Technology, Pohang 37673, Republic of Korea.
4
Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea.
5
Advanced Light Source, Lawrence Berkeley National Laboratory, California 94720, USA.
6
Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea.
7
Department of Physics and Division of Advanced Nuclear Engineering, Pohang University of Science and Technology, Pohang 37673, Republic of Korea.
8
Department of Physics, Sungkyunkwan University, Suwon 16419, Republic of Korea.
9
Department of Physics, Incheon National University, Incheon 22012, Republic of Korea.

Abstract

We investigate the hidden Berry curvature in bulk 2H-WSe_{2} by utilizing the surface sensitivity of angle resolved photoemission (ARPES). The symmetry in the electronic structure of transition metal dichalcogenides is used to uniquely determine the local orbital angular momentum (OAM) contribution to the circular dichroism (CD) in ARPES. The extracted CD signals for the K and K^{'} valleys are almost identical, but their signs, which should be determined by the valley index, are opposite. In addition, the sign is found to be the same for the two spin-split bands, indicating that it is independent of spin state. These observed CD behaviors are what are expected from Berry curvature of a monolayer of WSe_{2}. In order to see if CD-ARPES is indeed representative of hidden Berry curvature within a layer, we use tight binding analysis as well as density functional calculation to calculate the Berry curvature and local OAM of a monolayer WSe_{2}. We find that measured CD-ARPES is approximately proportional to the calculated Berry curvature as well as local OAM, further supporting our interpretation.

PMID:
30444409
DOI:
10.1103/PhysRevLett.121.186401
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