Phys. Rev. Applied 25, 044028 (2026)
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/⁢WSe₂ 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.