Intrinsic spin Hall effect in graphene: Numerical calculations in a multi-orbital mode

TL;DR

This paper investigates the spin Hall effect in graphene using a multi-orbital model with spin-orbit interaction, revealing small conductivity in metals and quantization violations in insulators, with doping as a potential enhancement method.

Contribution

It provides a detailed numerical analysis of the spin Hall effect in graphene considering multi-orbital and doping effects, which was not extensively studied before.

Findings

Spin Hall conductivity is small in metallic graphene.

Quantization of SHC is broken in insulating graphene due to multi-orbital effects.

Chemical doping can enhance the SHE in graphene.

Abstract

We study the spin Hall effect (SHE) in graphene using a realistic multi-orbital tight-binding model that includes the atomic spin-orbit interaction. The SHE is found to be induced by the spin-dependent Aharonov-Bohm phase. In the metallic case, the calculated values for the spin Hall conductivity (SHC) are much smaller than the quantized Hall conductivity for realistic parameter values of metallic graphene. In the insulating case, quantization of the SHC is violated due to the multi-orbital effect. The present study suggests that the SHE in a honeycomb lattice is enhanced by chemical doping, such as the substitution of carbon atoms with boron atoms.