Anomalous valley Hall effect and Nernst effect in strain engineered graphene

Abstract

Abstract Anomalous valley Hall effect (AVHE), which forwards a strategy for combining valleytronics and spintronics, has recently attracted much interest. Usually, this effect is associated with the anomalous velocity acquired by the carriers due to the Berry curvature of the Bloch bands. Here we propose a new strategy to generate AVHE in a graphene-based normal/strained/normal junction, where AVHE originates from the spin-valley tunneling asymmetry for the transmission through the junction. When the system is driven by a temperature bias, an anomalous valley Nernst effect is demonstrated, in which the transverse current is completely spin- and valley-polarized simultaneously. In particular, the thermally induced longitudinal charge current can become zero with the finite transverse one, causing the ratio between them to be infinite, which is usually small for the Hall effect. It is expected that our findings could provide potential applications in valleytronics and spintronics.