Strain Engineering of the Intrinsic Spin Hall Conductivity in a SrTiO$_3$ Quantum Well

TL;DR

This paper investigates how strain influences the intrinsic spin Hall conductivity in SrTiO$_3$ quantum wells, revealing that strain and gate voltage can significantly modify spin-charge conversion efficiency.

Contribution

It introduces a comprehensive tight-binding model to analyze strain effects on spin Hall conductivity in SrTiO$_3$ quantum wells, highlighting the importance of strain direction and gate voltage tuning.

Findings

Strain and gate voltage can tune the spin Hall conductivity.

Strain direction affects conduction band alignment.

Significant variation in spin-charge conversion ratio.

Abstract

The intrinsic spin Hall conductivity of a two-dimensional gas confined to SrTiO$_3$, such as occurs at an LaAlO$_3$/SrTiO$_3$ interface, is calculated from the Kubo formula. The effect of strain in the [001] (normal to the quantum well direction) and the [111] direction is incorporated into a full tight-binding Hamiltonian. We show that the spin-charge conversion ratio can be significantly altered through strain and gate voltage by tuning the chemical potential. Strain direction is also a significant factor in the spin Hall response as this direction affects the alignment of the conduction bands.