Spin Hall effect in the kagome lattice with Rashba spin-orbit interaction

TL;DR

This paper investigates the spin Hall effect in a kagome lattice with Rashba spin-orbit coupling, revealing quantized conductance plateaus linked to Fermi surface topology and highlighting potential for valley-specific spintronics.

Contribution

It provides a detailed numerical and analytical study of the spin Hall conductance in kagome lattices, including Berry-phase interpretation and the impact of Fermi surface topology.

Findings

Plateaus in spin Hall conductance linked to Fermi surface topology.

Enhanced conductance when Fermi surface encircles K points.

Potential applications in K-valley spintronics.

Abstract

We study the spin Hall effect in the kagom\'{e} lattice with Rashba spin-orbit coupling. The conserved spin Hall conductance $\sigma_{xy}^{s}$ (see text) and its two components, i.e., the conventional term $\sigma_{xy}^{s0}$ and the spin-torque-dipole term $\sigma_{xy}^{s\tau}$, are numerically calculated, which show a series of plateaus as a function of the electron Fermi energy $\epsilon_{F}$. A consistent two-band analysis, as well as a Berry-phase interpretation, is also given. We show that these plateaus are a consequence of the various Fermi-surface topologies when tuning $\epsilon_{F}$. In particular, we predict that compared to the case with the Fermi surface encircling the $\mathbf{\Gamma}$ point in the Brillouin zone, the amplitude of the spin Hall conductance with the Fermi surface encircling the $\mathbf{K}$ points is twice enhanced, which makes it highly meaningful in the future to systematically carry out studies of the $\mathbf{K}$-valley spintronics.