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 Dˉ, 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 Dˉ=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 8×8 model Hamiltonian of BLG/TMDC.
@article{arxiv.2012.05718,
title = {Counterintuitive gate dependence of weak antilocalization in bilayer graphene/WSe$_2$ heterostructures},
author = {Julia Amann and Tobias Völkl and Tobias Rockinger and Denis Kochan and Kenji Watanabe and Takashi Taniguchi and Jaroslav Fabian and Dieter Weiss and Jonathan Eroms},
journal= {arXiv preprint arXiv:2012.05718},
year = {2022}
}