Spin-helical Dirac states in graphene induced by polar-substrate surfaces with giant spin-orbit interaction: a new platform for spintronics

TL;DR

This paper presents a novel method to induce spin-helical Dirac states in graphene by coupling it with polar substrates exhibiting giant Rashba spin-splitting, advancing spintronics applications.

Contribution

It introduces a new pathway to create spin-polarized Dirac states in graphene through coupling with polar-substrate surface states with giant Rashba splitting.

Findings

Spin-helical Dirac states are formed in graphene on BiTeCl surface.

Coupling induces spin separation and in-plane spin polarization.

Potential for new spintronics device platforms.

Abstract

Spintronics, or spin electronics, is aimed at efficient control and manipulation of spin degrees of freedom in electron systems. To comply with demands of nowaday spintronics, the studies of electron systems hosting giant spin-orbit-split electron states have become one of the most important directions providing us with a basis for desirable spintronics devices. In construction of such devices, it is also tempting to involve graphene, which has attracted great attention because of its unique and remarkable electronic properties and was recognized as a viable replacement for silicon in electronics. In this case, a challenging goal is to make graphene Dirac states spin-polarized. Here, we report on absolutely new promising pathway to create spin-polarized Dirac states based on coupling of graphene and polar-substrate surface states with giant Rashba-type spin-splitting. We demonstrate how the spin-helical Dirac states are formed in graphene deposited on the surface of BiTeCl. This coupling induces spin separation of the originally spin-degenerate graphene states and results in fully helical in-plane spin polarization of the Dirac electrons.