Electric-Field-control of spin rotation in bilayer graphene

TL;DR

This paper demonstrates how a double-gate field-effect transistor with bilayer graphene and ferromagnetic oxide as a gate dielectric can electrically control spin precession, advancing spintronics applications.

Contribution

It introduces a novel device design that enables electrical switching of spin precession in bilayer graphene via proximity-induced exchange interaction.

Findings

Spin precession can be turned ON and OFF with gate voltage.

Spin-resolved conductance shows clear control of spin rotation.

Proximity effect enables effective spin manipulation in graphene.

Abstract

The manipulation of the electron spin degree of freedom is at the core of the spintronics paradigm, which offers the perspective of reduced power consumption, enabled by the decoupling of information processing from net charge transfer. Spintronics also offers the possibility of devising hybrid devices able to perform logic, communication, and storage operations. Graphene, with its potentially long spin-coherence length, is a promising material for spin-encoded information transport. However, the small spin-orbit interaction is also a limitation for the design of conventional devices based on the canonical Datta-Das spin-FET. An alternative solution can be found in magnetic doping of graphene, or, as discussed in the present work, in exploiting the proximity effect between graphene and Ferromagnetic Oxides (FOs). Graphene in proximity to FO experiences an exchange proximity interaction (EPI), that acts as an effective Zeeman field for electrons in graphene, inducing a spin precession around the magnetization axis of the FO. Here we show that in an appropriately designed double-gate field-effect transistor, with a bilayer graphene channel and FO used as a gate dielectric, spin-precession of carriers can be turned ON and OFF with the application of a differential voltage to the gates. This feature is directly probed in the spin-resolved conductance of the bilayer.