Topological surface state under graphene for two-dimensional spintronics in air

TL;DR

This paper demonstrates a giant Rashba effect on Ir(111) surface states that remains stable under graphene protection in air, suggesting potential for ambient spintronics applications.

Contribution

It reveals that graphene can protect topological surface states with giant Rashba effects from environmental degradation, enabling practical spintronics devices in air.

Findings

Giant Rashba effect ({}_R ~ 1.5E-10 eVm) observed on Ir(111) surface state

Spin splitting and polarization unaffected by graphene coverage

Surface state remains stable in ambient atmosphere under graphene protection

Abstract

Spin currents which allow for a dissipationless transport of information can be generated by electric fields in semiconductor heterostructures in the presence of a Rashba-type spin-orbit coupling. The largest Rashba effects occur for electronic surface states of metals but these cannot exist but under ultrahigh vacuum conditions. Here, we reveal a giant Rashba effect ({\alpha}_R ~ 1.5E-10 eVm) on a surface state of Ir(111). We demonstrate that its spin splitting and spin polarization remain unaffected when Ir is covered with graphene. The graphene protection is, in turn, sufficient for the spin-split surface state to survive in ambient atmosphere. We discuss this result along with evidences for a topological protection of the surface state.