Spin-Hall Effect and Diamagnetism of Dirac Electrons

TL;DR

This paper investigates the spin-Hall conductivity of relativistic Dirac electrons, revealing contributions from both near-Fermi and all occupied states, with implications for bismuth alloys and their diamagnetic properties.

Contribution

It uncovers a novel contribution to spin-Hall conductivity from all occupied states, linking it to diamagnetism in Dirac electron systems, and applies findings to bismuth-antimony alloys.

Findings

Two distinct contributions to SHC identified

SHC persists in insulating states with band-gap

SHC shows similar dependence to diamagnetism

Abstract

Spin-Hall conductivity (SHC) of fully relativistic (4x4 matrix) Dirac electrons is studied based on the Kubo formula aiming at possible application to bismuth and bismuth-antimony alloys. It is found that there are two distinct contributions to SHC, one only from the states near the Fermi energy and the other from all the occupied states. The latter remains even in the insulating state, i.e., when the chemical potential lies in the band-gap, and turns to have the same dependences on the chemical potential as the orbital susceptibility (diamagnetism), a surprising fact. These results are applied to bismuth-antimony alloys and the doping dependence of the SHC is proposed.