Proximity induced spin orbit effects in graphene on Au

TL;DR

This paper develops a theoretical model to explain the large spin-orbit coupling observed in graphene on gold, identifying key orbital interactions and configurations that enhance this effect, consistent with recent experiments.

Contribution

The authors introduce a $p_{z}-d$ coupling model Hamiltonian for graphene/Au that predicts large intrinsic spin-orbit coupling, aligning with experimental and DFT findings, and analyze different stacking configurations.

Findings

The model reproduces experimental spectra for different stacking registries.

The hollow site configuration yields the largest spin-orbit coupling enhancement.

Gold dilution preserves the spin-orbit gap with similar enhancement but reduces graphene-gold distance.

Abstract

We introduce a $p_{z}-d$ coupling model Hamiltonian for the $\pi$-graphene/Au bands that predicts a rather large intrinsic spin-orbit (SO) coupling as are being reported in recent experiments and DFT studies. Working within the analytical Slater-Koster tight-binding approach we were able to identify the overlapping orbitals of relevance in the enhancement of the SO coupling for both, the sublattice symmetric (BC), and the ATOP (AC) stacking configurations. Our model effective Hamiltonian reproduces quite well the experimental spectrum for the two registries, and in addition, its shows that the hollow site configuration (BC), in which the A/B sites remain symmetric, yields the larger increase of the SO coupling. We also explore the Au-diluted case keeping the BC configuration and showed that it renders the preservation of the SO-gap with a similar SO interaction enhancement as the undiluted case but with a smaller graphene-gold distance.