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arXiv · 1912.11306

Electrically tunable valley dynamics in twisted WSe$_2$/WSe$_2$ bilayers

Giovanni Scuri·Trond I. Andersen·You Zhou·Dominik S. Wild·Jiho Sung·Ryan J. Gelly·Damien Bérubé·Hoseok Heo·Linbo Shao·Andrew Y. Joe·Andrés M. Mier Valdivia·Takashi Taniguchi·Kenji Watanabe·Marko Lončar·Philip Kim·Mikhail D. Lukin·Hongkun Park
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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 WSe$_2$/WSe$_2$ 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 three 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.

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Giovanni Scuri, Trond I. Andersen, You Zhou, Dominik S. Wild, Jiho Sung, Ryan J. Gelly, Damien Bérubé, Hoseok Heo, Linbo Shao, Andrew Y. Joe, Andrés M. Mier Valdivia, Takashi Taniguchi, Kenji Watanabe, Marko Lončar, Philip Kim, Mikhail D. Lukin, Hongkun Park. 2019-12-24. Electrically tunable valley dynamics in twisted WSe$_2$/WSe$_2$ bilayers. https://doi.org/10.1103/physrevlett.124.217403

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