Valley Hall effect and nonlocal resistance in locally gapped graphene
Thomas Aktor, José H. García, Stephan Roche, Antti‐Pekka Jauho, Stephen R. Power
Abstract
We report on the emergence of bulk, valley-polarized currents in graphene-based devices, driven by spatially varying regions of broken sublattice symmetry, and revealed by nonlocal resistance (${R}_{\mathrm{NL}}$) fingerprints. By using a combination of quantum transport formalisms, giving access to bulk properties as well as multiterminal device responses, the presence of a nonuniform local band gap is shown to give rise to valley-dependent scattering and a finite Fermi-surface contribution to the valley Hall conductivity, related to characteristics of ${R}_{\mathrm{NL}}$. These features are robust against disorder and provide a plausible interpretation of controversial experiments in graphene/hexagonal boron nitride superlattices. Our findings suggest both an alternative mechanism for the generation of valley Hall effect in graphene and a route towards valley-dependent electron optics, by materials and device engineering.