Coupled spin and valley Hall effects driven by coherent tunneling

TL;DR

This paper predicts that coherent tunneling in graphene with broken inversion symmetry and spin-orbit coupling can generate coupled spin and valley Hall effects, enabling efficient spintronic and valleytronic device functionalities.

Contribution

It introduces a novel mechanism where coherent tunneling induces coupled spin and valley Hall effects via geometric phase effects in graphene.

Findings

Coherent tunneling causes spin- and valley-dependent Hall currents.

Charge-spin and charge-valley conversions are highly efficient.

Large Hall angles are achieved in the proposed mechanism.

Abstract

We predict the coexistence of tunneling spin and valley Hall effects when electrons in graphene coherently transmit through a barrier with the broken inversion symmetry and proximity-induced spin-orbit coupling. Due to the rotation of the pseudospin in the tunneling process, the transmitted electrons acquire a finite spin- and valley-dependent backreflection geometric phase when the two interfaces of the barrier are asymmetric. This results in a spin- and valley-dependent skew coherent tunneling, which is responsible for the transverse spin and valley Hall currents. We further demonstrate that the coherent-tunneling assisted charge-spin and charge-valley conversions are highly efficient with large Hall angles. Our work provides a new route for the generation of efficient spin and valley Hall effects, suggesting potential applications for spintronic and valleytronic devices.