Spin-Orbit Proximity Effect in Graphene

TL;DR

This paper demonstrates that placing graphene in contact with WS2 significantly enhances its spin-orbit coupling, enabling room-temperature spin Hall effects and potential spin FET applications, while also allowing defect detection in WS2.

Contribution

The study introduces a method to induce strong spin-orbit coupling in graphene via proximity to WS2 without structural modification, advancing spintronics device development.

Findings

Graphene acquires a 17 meV SOC when interfaced with WS2.

Proximity SOC enables room-temperature spin Hall effect in graphene.

Defects in WS2 influence the proximity-induced SOC in graphene.

Abstract

The development of a spintronics device relies on efficient generation of spin polarized currents and their electric field controlled manipulation. While observation of exceptionally long spin relaxation lengths make graphene an intriguing material for spintronics studies, modulation of spin currents by gate field is almost impossible due to negligibly small intrinsic spin orbit coupling (SOC) of graphene. In this work, we create an artificial interface between monolayer graphene and few-layers semiconducting tungsten disulfide (WS2). We show that in such devices graphene acquires a SOC as high as 17meV, three orders of magnitude higher than its intrinsic value, without modifying any of the structural properties of the graphene. Such proximity SOC leads to the spin Hall effect even at room temperature and opens the doors for spin FETs. We show that intrinsic defects in WS2 play an important role in this proximity effect and that graphene can act as a probe to detect defects in semiconducting surfaces.