Proximity-induced spin-orbit coupling in bilayer graphene/WSe₂ heterostructures probed by quantum Hall measurements

The physical properties of 2D materials are highly sensitive to the interface in a van der Waals heterostructure [1], leading to intensive studies into the resulting proximity effects. In particular, significant effort has been made to increase the spin-orbit coupling (SOC) in graphene by coupling it to transition metal dichalcogenides [2]. However, it remains challenging to study high-quality quantum Hall signatures, which acts as a precise probe of SOC strength [3]. Here we report a direct observation of SOC in a bilayer graphene/WSe₂ heterostructure in quantum Hall measurements [4]. A distinct Landau level (LL) crossing pattern emerges when tuning the charge density and displacement field, originating from a layer-selective SOC proximity effect. By analyzing the LL structure, we simultaneously estimate both Ising (~-2.2 meV) and Rashba SOC (~15 meV) energy scales, which are consistent with the theoretical predictions of interlayer twist angle dependence. Our study provides a high mobility system with potential to realize novel topological electronic states and manipulate spin in nanostructures.
[1] A. K. Geim, et al. Nature 2013 499, 419
[2] A. Avsar, et al. Nat. Commun. 2014, 5, 4875
[3] J. O. Island, et al. Nature 2019 571, 85
[4] D. Wang, et al. Nano Lett. 2019 19 (10), 7028