Curvature-induced spin-orbit coupling and spin relaxation in a chemically clean single-layer graphene

TL;DR

This paper theoretically investigates how nanoscale curvature in single-layer graphene induces two types of spin-orbit coupling, affecting spin relaxation, with implications for spintronic applications in clean, corrugated graphene.

Contribution

It identifies a new type of curvature-induced spin-orbit coupling in graphene that does not couple with pseudospin, expanding understanding beyond previous models.

Findings

Both types of curvature-induced spin-orbit coupling contribute equally to spin relaxation.

Spin relaxation depends on the roughness of the graphene corrugation.

A new pseudospin-independent spin-orbit coupling mechanism is proposed.

Abstract

The study of spin-related phenomena in materials requires knowledge on the precise form of effective spin-orbit coupling of conducting carriers in the solid-states systems. We demonstrate theoretically that curvature induced by corrugations or periodic ripples in single-layer graphenes generates two types of effective spin-orbit coupling. In addition to the spin-orbit coupling reported previously that couples with sublattice pseudospin and corresponds to the Rashba-type spin-orbit coupling in a corrugated single-layer graphene, there is an additional spin-orbit coupling that does not couple with the pseudospin, which can not be obtained from the extension of the curvature-induced spin-orbit coupling of carbon nanotubes. Via numerical calculation we show that both types of the curvature-induced spin-orbit coupling make the same order of contribution to spin relaxation in chemically clean single-layer graphene with nanoscale corrugation. The spin relaxation dependence on the corrugation roughness is also studied.