Intrinsic orbital and spin Hall effect in bismuth semimetal

TL;DR

This paper explores the intrinsic orbital and spin Hall effects in bismuth semimetal, revealing their anisotropic behaviors and the dominant role of spin-orbit coupling in generating large spin Hall conductivity.

Contribution

It demonstrates the distinct anisotropy of orbital and spin Hall conductivities and clarifies the influence of spin-orbit coupling on their relationship in bismuth semimetal.

Findings

Significant anisotropy between OHC and SHC within the basal plane.

Weak correlation between orbital and spin Berry curvatures at the Fermi energy.

Large SHC primarily due to strong spin-orbit coupling effects.

Abstract

We investigate the intrinsic orbital Hall conductivity (OHC) and spin Hall conductivity (SHC) in a bismuth semimetal, by employing an sp-orbital tight-binding model. We report a notable difference between the anisotropy of OHC and SHC whose orbital and spin polarizations lie within the basal plane. We do not observe a substantial correlation between the orbital and spin Berry curvatures with spin-orbit coupling (SOC) at the Fermi energy, disproving the correlation between OHC and SHC in a strong SOC regime. We argue the huge SHC in a Bi semimetal is attributed to its gigantic SOC which strongly affects the hybridization of the p orbitals, despite its relatively small magnitude of OHC. We hope the distinct anisotropy of OHC and SHC provides a feasible means to differentiate between the two effects in experiments.