Thin film of a topological insulator as a spin Hall insulator

TL;DR

This paper investigates the spin conductivity of surface states in thin topological insulator films, revealing finite conductivity in the gapped region and enhancement near the band gap, highlighting potential for spintronic applications.

Contribution

It provides a theoretical analysis of spin conductivity in topological insulator thin films, emphasizing the effects of hybridization and the resulting implications for spintronics.

Findings

Spin conductivity remains finite in the gapped region.

Spin conductivity is enhanced near the band gap.

Thin films are promising for spintronic devices.

Abstract

We study spin conductivity of the surface states in a thin film of a topological insulator with Kubo formulas. Hybridization between the different sides of the film opens a gap at the Dirac point. We found that in the gapped region spin conductivity remains finite. In the gapless region near the band gap spin conductivity is enhanced. These findings make a thin film of a topological insulator as a promising material for spintronic applications.