Disentangling electronic and phononic thermal transport across two-dimensional interfaces

Electrical and thermal transport at two-dimensional (2D) interfaces is critical for semiconductor technology, yet their interplay remains unclear. We report a theoretical proposal to separate electronic and phononic contributions to thermal conductance at 2D interfaces with graphene, which is validated by non-equilibrium Green's function calculations and molecular dynamics simulations for graphene-gold contacts. Our results reveal that while metal-graphene interfaces are transparent for both electrons and phonons, non-covalent graphene interfaces block electronic tunneling beyond two layers but not phonon transport. This suggests that the Wiedemann-Franz law can be experimentally tested by measuring transport across interfaces with varying graphene layers.