Generation and detection of pure valley current by electrically induced Berry curvature in bilayer graphene

TL;DR

This paper demonstrates how electrically induced Berry curvature in dual-gated bilayer graphene can generate and detect pure valley currents, advancing non-dissipative electronic applications.

Contribution

It introduces a method to electrically control and detect pure valley currents in bilayer graphene via Berry curvature manipulation.

Findings

Large nonlocal resistance observed in insulating regime

Cubic scaling between nonlocal resistance and local resistivity

Electrical control enables non-dissipative valley current induction

Abstract

Valley is a useful degree of freedom for non-dissipative electronics since valley current that can flow even in an insulating material does not accompany electronic current. We use dual-gated bilayer graphene in the Hall bar geometry to electrically control broken inversion symmetry or Berry curvature as well as the carrier density to generate and detect the pure valley current. We find a large nonlocal resistance and a cubic scaling between the nonlocal resistance and the local resistivity in the insulating regime at zero-magnetic field and 70 K as evidence of the pure valley current. The electrical control of the valley current in the limit of zero conductivity allows non-dissipative induction of valley current from electric field and thus provides a significant contribution to the advancement of non-dissipative electronics.