On-Demand Spin-Orbit Interaction from Which-Layer Tunability in Bilayer Graphene

TL;DR

This paper presents a method to achieve highly tunable spin-orbit interaction in bilayer graphene by shifting carriers between layers using an electric field, enabling ON/OFF switching and new spin control possibilities.

Contribution

The study introduces a novel approach for on-demand, broad-range tunability of spin-orbit interaction in graphene multilayers via which-layer inhomogeneity.

Findings

Complete tunability and ON/OFF switching of SOI in bilayer graphene.

Demonstration of electrically driven spin resonance.

Potential for topological phases with different valley Hall conductivities.

Abstract

Spin-orbit interaction (SOI) that is gate-tunable over a broad range is essential to exploiting novel spin phenomena. Achieving this regime has remained elusive because of the weakness of the underlying relativistic coupling and lack of its tunability in solids. Here we outline a general strategy that enables exceptionally high tunability of SOI through creating a which-layer spin-orbit field inhomogeneity in graphene multilayers. An external transverse electric field is applied to shift carriers between the layers with strong and weak SOI. Because graphene layers are separated by sub-nm scales, exceptionally high tunability of SOI can be achieved through a minute carrier displacement. A detailed analysis of the experimentally relevant case of bilayer graphene on a semiconducting transition metal dichalchogenide substrate is presented. In this system, a complete tunability of SOI amounting to its ON/OFF switching can be achieved. New opportunities for spin control are exemplified with electrically driven spin resonance and topological phases with different quantized intrinsic valley Hall conductivities.