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Electrically Tunable Valley Dynamics in Twisted WSe₂/WSe₂ Bilayers

Scuri, Giovanni and Andersen, Trond I. and Zhou, You and Wild, Dominik S. and Sung, Jiho and Gelly, Ryan J. and Bérubé, Damien and Heo, Hoseok and Shao, Linbo and Joe, Andrew Y. and Mier Valdivia, Andrés M. and Taniguchi, Takashi and Watanabe, Kenji and Lončar, Marko and Kim, Philip and Lukin, Mikhail D. and Park, Hongkun (2020) Electrically Tunable Valley Dynamics in Twisted WSe₂/WSe₂ Bilayers. Physical Review Letters, 124 (21). Art. No. 217403. ISSN 0031-9007. doi:10.1103/physrevlett.124.217403.

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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.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Scuri, Giovanni0000-0003-1050-3114
Zhou, You0000-0002-9854-545X
Shao, Linbo0000-0002-0615-7848
Joe, Andrew Y.0000-0003-4376-7386
Watanabe, Kenji0000-0003-3701-8119
Lončar, Marko0000-0002-5029-5017
Park, Hongkun0000-0001-9576-8829
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.
Funding AgencyGrant Number
Vannevar Bush FellowshipUNSPECIFIED
Office of Naval Research (ONR)N00014-16-1-2825
Office of Naval Research (ONR)N00014-18-1-2877
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 FoundationGBMF4543
Office of Naval Research (ONR)N00014-15-1-2761
Samsung ElectronicsUNSPECIFIED
Ministry of Education, Culture, Sports, Science and Technology (MEXT)UNSPECIFIED
Japan Science and Technology Agency (JST)JPMJCR15F3
Issue or Number:21
Record Number:CaltechAUTHORS:20200528-151011130
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:103531
Deposited By: Tony Diaz
Deposited On:28 May 2020 22:22
Last Modified:16 Nov 2021 18:22

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