Weak localization as a probe of spin-orbit-induced spin-split bands in bilayer graphene proximity coupled to WSe 2

Proximity coupling of bilayer graphene (BLG) to transition metal dichalcogenides (TMDs) offers a promising route to engineer gate-tunable spin-orbit coupling (SOC) while preserving BLG’s exceptional electronic properties. This tunability arises from the layer-asymmetric electronic structure of gapped BLG, where SOC acts predominantly on the layer in contact with the TMD. Here, we present a high-quality BLG / WSe 2 device with a proximity-induced SOC gap and excellent electrostatic control. Operating in a quasiballistic regime, our double-gated heterostructure allows a gate-defined p - n - p cavity to be formed and clear weak antilocalization (WAL) features to be shown consistent with Rashba-type SOC. At lower hole densities, a transition to a pronounced weak-localization (WL) feature is observed, signaling transport through a single spin-split valence band. These findings–in agreement with calculations–provide direct spectroscopic evidence of a proximity-induced spin-split band in BLG and underscore the potential of BLG/TMD heterostructures for spintronics and spin-based quantum technologies.