Electrically Tunable Valley Dynamics in Twisted WSe₂/WSe₂ Bilayers
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
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Additional details
- Eprint ID
- 103531
- Resolver ID
- CaltechAUTHORS:20200528-151011130
- Vannevar Bush Fellowship
- N00014-16-1-2825
- Office of Naval Research (ONR)
- N00014-18-1-2877
- Office of Naval Research (ONR)
- PHY-1506284
- NSF
- PHY-1125846
- NSF
- FA9550-17-1-0002
- Air Force Office of Scientific Research (AFOSR)
- FA9550-09-1-0042
- Air Force Office of Scientific Research (AFOSR)
- W911NF1520067
- Army Research Office (ARO)
- GBMF4543
- Gordon and Betty Moore Foundation
- N00014-15-1-2761
- Office of Naval Research (ONR)
- Samsung Electronics
- ECCS-1541959
- NSF
- Ministry of Education, Culture, Sports, Science and Technology (MEXT)
- JPMJCR15F3
- Japan Science and Technology Agency (JST)
- Created
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2020-05-28Created from EPrint's datestamp field
- Updated
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2021-11-16Created from EPrint's last_modified field