CaltechAUTHORS
Published May 29, 2020 | Version Supplemental Material + Submitted + Published
Journal Article Open

Electrically Tunable Valley Dynamics in Twisted WSe₂/WSe₂ Bilayers

Creators

  • 1. ROR icon Harvard University
  • 2. ROR icon California Institute of Technology
  • 3. ROR icon National Institute for Materials Science

Abstract

The twist degree of freedom provides a powerful new tool for engineering the electrical and optical properties of van der Waals heterostructures. Here, we show that the twist angle can be used to control the spin-valley properties of transition metal dichalcogenide bilayers by changing the momentum alignment of the valleys in the two layers. Specifically, we observe that the interlayer excitons in twisted WSe₂/WSe₂ bilayers exhibit a high (>60%) degree of circular polarization (DOCP) and long valley lifetimes (>40  ns) at zero electric and magnetic fields. The valley lifetime can be tuned by more than 3 orders of magnitude via electrostatic doping, enabling switching of the DOCP from ∼80% in the n-doped regime to <5% in the p-doped regime. These results open up new avenues for tunable chiral light-matter interactions, enabling novel device schemes that exploit the valley degree of freedom.

Additional Information

© 2020 American Physical Society. Received 14 December 2019; accepted 6 May 2020; published 28 May 2020. We acknowledge support from the Department of Defense Vannevar Bush Faculty Fellowship (N00014-16-1-2825 for H. P. and N00014-18-1-2877 for P. K.), NSF (PHY-1506284 for H. P. and M. D. L.), NSF CUA (PHY-1125846 for H. P. and M. D. L.), AFOSR MURI (FA9550-17-1-0002 for H. P., M. D. L. and P. K.), AFOSR DURIP (FA9550-09-1-0042 for M. L.), ARL (W911NF1520067 for H. P. and M. D. L.), the Gordon and Betty Moore Foundation (GBMF4543 for P. K.), ONR MURI (N00014-15-1-2761 for P. K.), and Samsung Electronics (for P. K. and H. P.). All fabrication was performed at the Center for Nanoscale Systems (CNS), a member of the National Nanotechnology Coordinated Infrastructure Network (NNCI), which is supported by the National Science Foundation under NSF Grant No. 1541959. K. W. and T. T. acknowledge support from the Elemental Strategy Initiative conducted by the MEXT, Japan, and the CREST (JPMJCR15F3), JST.

Attached Files

Published - PhysRevLett.124.217403.pdf

Submitted - 1912.11306.pdf

Supplemental Material - Supplemental_Material_FINAL_refs.pdf

Files

1912.11306.pdf

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Additional details

Identifiers

Eprint ID
103531
Resolver ID
CaltechAUTHORS:20200528-151011130

Related works

Describes
https://arxiv.org/abs/1912.11306 (URL)

Funding

Vannevar Bush Fellowship
Office of Naval Research (ONR)
N00014-16-1-2825
Office of Naval Research (ONR)
N00014-18-1-2877
NSF
PHY-1506284
NSF
PHY-1125846
Air Force Office of Scientific Research (AFOSR)
FA9550-17-1-0002
Air Force Office of Scientific Research (AFOSR)
FA9550-09-1-0042
Army Research Office (ARO)
W911NF1520067
Gordon and Betty Moore Foundation
GBMF4543
Office of Naval Research (ONR)
N00014-15-1-2761
Samsung Electronics
NSF
ECCS-1541959
Ministry of Education, Culture, Sports, Science and Technology (MEXT)
Japan Science and Technology Agency (JST)
JPMJCR15F3

Dates

Created
2020-05-28
Created from EPrint's datestamp field
Updated
2021-11-16
Created from EPrint's last_modified field