Calculation of intrinsic spin Hall conductivity by Wannier interpolation

TL;DR

This paper introduces an efficient Wannier interpolation method for calculating intrinsic spin Hall conductivity from first principles, reducing computational cost and improving accuracy for complex materials.

Contribution

The authors develop a Wannier-based scheme that simplifies and accelerates the calculation of spin Hall conductivity from ab-initio data, enabling large-scale material screening.

Findings

Validated on fcc Pt and GaAs with high accuracy.

Showed $eta$-Ta has 2.7 times the SHC of $ ext{alpha}$-Ta.

Calculated spin Hall angle of $eta$-Ta matches experiments.

Abstract

\textit{Ab-initio} calculation of intrinsic spin Hall conductivity (SHC) generally requires a strict convergence criterion and a dense k-point mesh to sample the Brillouin zone, making its convergence challenging and time-consuming. Here we present a scheme for efficiently and accurately calculating SHC based on maximally localized Wannier function (MLWF). The quantities needed by the Kubo formula of SHC are derived in the space of MLWF and it is shown that only the Hamiltonian, the overlap and the spin operator matrices are required from the initial \textit{ab-initio} calculation. The computation of these matrices and the interpolation of Kubo formula on a dense k-point mesh can be easily achieved. We validate our results by prototypical calculations on fcc Pt and GaAs, which demonstrate that the Wannier interpolation approach is of high accuracy and efficiency. Calculations of $\alpha$-Ta and $\beta$-Ta show that SHC of $\beta$-Ta is 2.7 times of $\alpha$-Ta, while both have the opposite sign relative to fcc Pt and are an order of magnitude smaller than Pt. The calculated spin Hall angle of $-0.156$, is quite consistent with previous experiment on $\beta$-Ta, further suggesting intrinsic contribution may dominate in $\beta$-Ta. Our approach could facilitate large-scale SHC calculations, and may benefit the discovery of materials with high intrinsic SHC.