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Title: Direct Measurement of the Tunable Electronic Structure of Bilayer MoS 2 by Interlayer Twist

We measure the interlayer twist angle-dependent electronic band structure of bilayer molybdenum-disulfide (MoS 2), using angle-resolved photoemission on micrometer-scale sample areas. Our measurements, performed on arbitrarily stacked bilayer MoS 2 flakes prepared by chemical vapor deposition, provide direct evidence for a downshift of the quasiparticle energy of the valence band at the Brillouin zone center ($$\bar{Γ}$$ point) with the interlayer twist angle, up to a maximum of 120 meV at a twist angle of ~40°. Our direct measurements of the valence band structure enable the extraction of the hole effective mass as a function of the interlayer twist angle. While our results at $$\bar{Γ}$$ agree with recently published photoluminescence data, our measurements of the quasiparticle spectrum over the full 2D Brillouin zone reveal a richer and more complicated change in the electronic structure than previously theoretically predicted. Furthermore, the electronic structure measurements reported here, including the evolution of the effective mass with twist-angle, provide new insight into the physics of twisted transition-metal dichalcogenide bilayers and serve as a guide for the practical design of MoS 2 optoelectronic and spin-/valley-tronic devices.
Authors:
 [1] ;  [2] ;  [2] ;  [3] ;  [4] ;  [4] ;  [5] ;  [1] ;  [6] ;  [4] ;  [7]
  1. Columbia Univ., New York, NY (United States). Dept. of Electrical Engineering
  2. Columbia Univ., New York, NY (United States). Dept. of Applied Physics and Applied Mathematics
  3. Columbia Univ., New York, NY (United States). Dept. of Chemistry; Technical Univ. of Dresden (Germany). Theoretical Chemistry
  4. Columbia Univ., New York, NY (United States). Dept. of Mechanical Engineering
  5. Brookhaven National Lab. (BNL), Upton, NY (United States). Center for Funcational Nanomaterials
  6. Univ. of Nebraska, Lincoln, NE (United States). Dept. of Electrical and Computer Engineering
  7. Columbia Univ., New York, NY (United States). Dept. of Electrical Engineering and Dept. of Applied Physics and Applied Mathematics
Publication Date:
Report Number(s):
BNL-111779-2016-JA
Journal ID: ISSN 1530-6984; R&D Project: 16083/16083; KC0403020
Grant/Contract Number:
SC00112704
Type:
Accepted Manuscript
Journal Name:
Nano Letters
Additional Journal Information:
Journal Volume: 16; Journal Issue: 2; Journal ID: ISSN 1530-6984
Publisher:
American Chemical Society
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; low energy electron microscopy (LEEM); MoS2; photoemission; spectromicroscopy; Stacked van der Waals structures; twisted van der Waals materials
OSTI Identifier:
1335381