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arXiv · 2012.05718

Counterintuitive gate dependence of weak antilocalization in bilayer graphene/WSe$_2$ heterostructures

Julia Amann·Tobias Völkl·Tobias Rockinger·Denis Kochan·Kenji Watanabe·Takashi Taniguchi·Jaroslav Fabian·Dieter Weiss·Jonathan Eroms
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Abstract

Strong gate control of proximity-induced spin-orbit coupling was recently predicted in bilayer graphene/transition metal dichalcogenides (BLG/TMDC) heterostructures, as charge carriers can easily be shifted between the two graphene layers, and only one of them is in close contact to the TMDC. The presence of spin-orbit coupling can be probed by weak antilocalization (WAL) in low field magnetotransport measurements. When the spin-orbit splitting in such a heterostructure increases with the out of plane electric displacement field $\bar D$, one intuitively expects a concomitant increase of WAL visibility. Our experiments show that this is not the case. Instead, we observe a maximum of WAL visibility around $\bar D=0$. This counterintuitive behaviour originates in the intricate dependence of WAL in graphene on symmetric and antisymmetric spin lifetimes, caused by the valley-Zeeman and Rashba terms, respectively. Our observations are confirmed by calculating spin precession and spin lifetimes from an $8\times 8$ model Hamiltonian of BLG/TMDC.

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Julia Amann, Tobias Völkl, Tobias Rockinger, Denis Kochan, Kenji Watanabe, Takashi Taniguchi, Jaroslav Fabian, Dieter Weiss, Jonathan Eroms. 2020-12-10. Counterintuitive gate dependence of weak antilocalization in bilayer graphene/WSe$_2$ heterostructures. https://doi.org/10.1103/physrevb.105.115425

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