k-dependent modulation of intrinsic spin-orbit interaction in MoSe₂ induced by proximity to amorphous Pb

Tuning the strength of spin-orbit interaction (SOI) is pivotal for developing next-generation spintronic and quantum devices. Proximity-induced SOI is a promising route toward this goal, but its experimental characterization with resolution in k-space using ARPES remains challenging. We advance previous ARPES investigations of proximity-induced SOI in graphene-based systems to transition-metal dichalcogenides (MoSe₂) in proximity to an amorphous overlayer of high-Z metal (Pb) whose disordered nature suppresses k-space mismatch at the interface. The use of soft-X-ray ARPES is instrumental for accessing MoSe₂ beneath the Pb layer. We introduce an approach to interpret the experimental data based on the identification of local SOI-derived band gaps-SOI hotspots-where the intrinsic SOI contribution, arising from the SOI field transfer from the overlayer to the host, is isolated from competing effects such as scalar (non-SOI) hybridization, interlayer interactions and Rashba-type splitting. We find that the proximity to Pb strongly enhances the intrinsic SOI as manifested by k-dependent increase of the band splitting in the SOI hotspots by  up to several tens of meV. Tunability of this effect via Pb coverage provides versatile means for tailoring SOI to specific spintronic and quantum applications.