Berry phase mediated topological thermoelectric transport in gapped single and bilayer graphene

TL;DR

This paper investigates how Berry phase effects induce a spontaneous transverse thermoelectric voltage in gapped graphene, enabling valley polarization without magnetic fields, with implications for valleytronics.

Contribution

It demonstrates that Berry phase effects can mediate an anomalous Nernst effect in gapped graphene, revealing a new mechanism for thermoelectric and valleytronic phenomena.

Findings

Berry phase induces transverse thermoelectric voltage

Valley polarization can be achieved via Nernst response

Spontaneous anomalous Nernst effect in gapped graphene

Abstract

We consider the anomalous thermoelectric transport in gapped single and bilayer graphene where the gap may be due to broken inversion symmetry. In the presence of the gap, non-trivial Berry phase effects can be shown to mediate a transverse thermoelectric voltage in response to an applied temperature gradient even in the absence of a perpendicular magnetic field. This spontaneous, anomalous Nernst effect is nonzero for non-uniform chemical potential in the two inequivalent valleys in the graphene band structure. Conversely, the Nernst response can be used to create a valley-index polarization between the two transverse sample edges as in the analogous valley Hall effect.