Electric field controlled valley-polarized photocurrent switch based on the circular bulk photovoltaic effect

TL;DR

This paper proposes an electric field-controlled method to switch valley-polarized photocurrents in 2D materials by manipulating Berry curvature, enabling potential valleytronic devices.

Contribution

It introduces a novel electrical scheme using a two-band Dirac model to control valley-polarized photocurrents via Berry curvature sign change.

Findings

Switching of valley-polarized photocurrent is linked to Berry curvature sign flip.

The scheme is validated in monolayer BiAsI2 and germanene.

Potential for valley-based memory devices is demonstrated.

Abstract

Efficient electric manipulation of valley degrees of freedom is critical and challenging for the advancement of valley-based information science and technology. We put forth an electrical scheme, based on a two-band Dirac model, that can switch the fully valley-polarized photocurrent between K and K' valleys using the circular bulk electro-photovoltaic effect. This is accomplished by applying an out-of-plane electric field to the two-dimensional valley materials, which enables continuous tuning of the Berry curvature and its sign flip. We found that the switch of the fully valley-polarized photocurrent is directly tied to the sign change of Berry curvature, which accompanies a topological phase transition, for instance, the quantum spin Hall effect and the quantum valley Hall effect. This scheme has been confirmed in monolayer BiAsI2 and germanene through first-principles calculations. Our paper offers a promising strategy for the development of a volatile valley-addressable memory device and could inspire further research in this area.