Spin Hall effect in a Kagome lattice driven by Rashba spin-orbit interaction

TL;DR

This paper numerically investigates the spin Hall conductance in a finite kagome lattice with Rashba spin-orbit interaction, revealing how external parameters and magnetic flux influence the spin Hall effect's behavior and sign.

Contribution

It provides a detailed numerical analysis of spin Hall conductance in a finite kagome lattice, highlighting the effects of magnetic flux and system parameters on SHE, which was less understood in finite geometries.

Findings

SHC changes sign depending on Fermi energy and band structure.

External magnetic flux reduces SHC and disrupts periodicity.

At specific flux values, SHE features reappear due to restored periodicity.

Abstract

Using four-terminal Landauer-B\"{u}ttiker formalism and Green's function technique, in this present paper, we calculate numerically spin Hall conductance (SHC) and longitudinal conductance of a finite size kagome lattice with Rashba spin-orbit (SO) interaction both in presence and absence of external magnetic flux in clean limit. In the absence of magnetic flux, we observe that depending on the Fermi surface topology of the system SHC changes its sign at different values of Fermi energy, along with the band center. Unlike the infinite system (where SHC is a universal constant $\pm \frac{e}{8 \pi}$), here SHC depends on the external parameters like SO coupling strength, Fermi energy, etc. We show that in the presence of any arbitrary magnetic flux, periodicity of the system is lost and the features of SHC tends to get reduced because of elastic scattering. But again at some typical values of flux ($\phi=1/2, 1/4, 3/4..., etc.) the system retains its periodicity depending on its size and the features of spin Hall effect (SHE) reappears. Our predicted results may be useful in providing a deeper insight into the experimental realization of SHE in such geometries.