Density-functional studies of spin-orbit splitting in graphene on metals

TL;DR

This study uses density-functional theory to analyze spin-orbit splitting in graphene on Ni, Au, and Ag substrates, revealing hybridization effects as the main cause of Rashba splitting, which enhances understanding of metal-induced spin phenomena in graphene.

Contribution

The paper provides a theoretical explanation for Rashba splitting in graphene on different metal substrates, emphasizing hybridization over charge transfer as the primary mechanism.

Findings

Rashba splitting of a few to tens of meV observed on all substrates.

Strong splitting on Au and Ag is mainly due to hybridization with metal d-states.

Charge transfer is not the main cause of the observed splitting.

Abstract

Spin-orbit splitting in graphene on Ni, Au, or Ag (111) substrates was examined on the basis of density-functional theory. Graphene grown on the three metals was found to have Rashba splitting of a few or several tens of meV. The strong splitting obtained on Au or Ag substrates was mainly ascribed to effective hybridization of graphene $p_{z}$ state with Au or Ag $d_{z^{2}}$ states, rather than charge transfer as previously proposed. Our work provides theoretical understandings of the metal-induced Rashba effect in graphene.