Imaging conductive nano-domains induced by Gd intercalation in epitaxial bilayer graphene

We report nano-infrared (IR) imaging and spectroscopy of epitaxial bilayer graphene (BLG) on silicon carbide (SiC) partially intercalated with gadolinium (Gd). Gd intercalation produces a high density of nanoscale conducting domains that exhibit pronounced IR enhancement at frequencies above the SiC phonon resonance and pronounced amplitude suppression at the resonance. Both effects originate from the increased local optical conductivity induced by Gd. Quantitative modeling of the nano-IR spectra shows that the conductivity of intercalated regions is enhanced by more than a factor of two relative to pristine BLG. This enhancement is attributed to the electronic decoupling of the graphene layers combined with substantial charge transfer from the intercalated atoms. These results demonstrate that controlled metal intercalation enables spatially resolved tuning of the electronic and optical responses of wafer-scale graphene, providing a versatile platform for graphene-based optoelectronic and nanophotonic applications.