Spin-orbit coupling in hydrogenated graphene

TL;DR

This paper investigates how hydrogen adatoms enhance spin-orbit coupling in graphene, revealing significant local effects and proposing minimal models to describe these phenomena based on symmetry considerations.

Contribution

It provides first-principles calculations of spin-orbit effects in hydrogenated graphene and introduces minimal Hamiltonians capturing the key physics.

Findings

Hydrogen adatoms cause a giant local enhancement of spin-orbit coupling.

The spin-orbit effects depend strongly on local lattice distortions.

Minimal Hamiltonians successfully reproduce the main spin-orbit features.

Abstract

First-principles calculations of the spin-orbit coupling in graphene with hydrogen adatoms in dense and dilute limits are presented. The chemisorbed hydrogen induces a giant local enhancement of spin-orbit coupling due to $sp^3$ hybridization which depends strongly on the local lattice distortion. Guided by the reduced symmetry and the local structure of the induced dipole moments we use group theory to propose realistic minimal Hamiltonians that reproduce the relevant spin-orbit effects for both single-side semihydrogenated graphene (graphone) and for a single hydrogen adatom in a large supercell. The principal linear spin-orbit band splittings are driven by the breaking of the local pseudospin inversion symmetry and the emergence of spin flips on the same sublattice.