title: Probing Critical Point Energies of Transition Metal Dichalcogenides: Surprising Indirect Gap of Single Layer WSe2.
abstract: By using a comprehensive form of scanning tunneling spectroscopy, we have revealed detailed quasi-particle electronic structures in transition metal dichalcogenides, including the quasi-particle gaps, critical point energy locations, and their origins in the Brillouin zones. We show that single layer WSe2 surprisingly has an indirect quasi-particle gap with the conduction band minimum located at the Q-point (instead of K), albeit the two states are nearly degenerate. We have further observed rich quasi-particle electronic structures of transition metal dichalcogenides as a function of atomic structures and spin-orbit couplings. Such a local probe for detailed electronic structures in conduction and valence bands will be ideal to investigate how electronic structures of transition metal dichalcogenides are influenced by variations of local environment.
authors.affiliation: Department of Physics, University of Texas at Austin , Austin, Texas 78712, United States.
authors.forename: Chendong
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Department of Physics, University of Texas at Austin , Austin, Texas 78712, United States.
authors.forename: Yuxuan
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Department of Physics, University of Texas at Austin , Austin, Texas 78712, United States.
authors.forename: Amber
authors.initials: A
authors.lastname: Johnson
authors.affiliation: Institute of Atomic and Molecular Sciences, Academia Sinica , No. 1, Roosevelt Road, Section 4, Taipei 10617, Taiwan.|Physical Sciences and Engineering Division, King Abdullah University of Science and Technology , Thuwal, 23955-6900, Kingdom of Saudi Arabia.
authors.forename: Ming-Yang
authors.initials: MY
authors.lastname: Li
authors.affiliation: Physical Sciences and Engineering Division, King Abdullah University of Science and Technology , Thuwal, 23955-6900, Kingdom of Saudi Arabia.
authors.forename: Lain-Jong
authors.initials: LJ
authors.lastname: Li
authors.affiliation: Department of Physics, Carnegie Mellon University , Pittsburgh, Pennsylvania 15213, United States.
authors.forename: Patrick C
authors.initials: PC
authors.lastname: Mende
authors.affiliation: Department of Physics, Carnegie Mellon University , Pittsburgh, Pennsylvania 15213, United States.
authors.forename: Randall M
authors.initials: RM
authors.lastname: Feenstra
authors.affiliation: Department of Physics, University of Texas at Austin , Austin, Texas 78712, United States.
authors.forename: Chih-Kang
authors.initials: CK
authors.lastname: Shih
mesh_terms: D018011:Chalcogens / Q000737:chemistry*; D016252:Microscopy, Scanning Tunneling; D028561:Transition Elements / Q000737:chemistry*
chemical_list: D018011:Chalcogens; D028561:Transition Elements
keywords: Transition metal dichalcogenides; critical points in Brillouin zones; interlayer coupling; scanning tunneling spectroscopy; spin−orbit coupling; variable Z spectroscopy