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arXiv · 1910.00489

Valley Hall Effect and Non-Local Resistance in Locally Gapped Graphene

Thomas Aktor·Jose H. Garcia·Stephan Roche·Antti-Pekka Jauho·Stephen R. Power
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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 non-local resistance ($R_\mathrm{NL}$) fingerprints. By using a combination of quantum transport formalisms, giving access to bulk properties as well as multi-terminal device responses, the presence of a non-uniform local bandgap 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/hBN 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.

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Thomas Aktor, Jose H. Garcia, Stephan Roche, Antti-Pekka Jauho, Stephen R. Power. 2019-10-01. Valley Hall Effect and Non-Local Resistance in Locally Gapped Graphene. https://doi.org/10.1103/physrevb.103.115406

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