Theory of charge-spin conversion at oxide interfaces: The inverse spin-galvanic effect

TL;DR

This paper investigates how electric fields induce non-equilibrium spin polarization at oxide interfaces, analyzing the effects of spin-orbit coupling, inversion asymmetry, disorder, and temperature on the inverse spin-galvanic effect.

Contribution

It provides a combined analytic and numerical study of spin polarization behavior at LAO/STO interfaces, accounting for disorder and temperature effects, offering a framework for experimental interpretation.

Findings

Spin polarization sign depends on chemical potential and band filling.

Disorder causes a transition from non-monotonous to monotonous behavior with temperature.

Results align with recent experimental observations.

Abstract

We evaluate the non-equilibrium spin polarization induced by an applied electric field for a tight-binding model of electron states at oxides interfaces in LAO/STO heterostructures. By a combination of analytic and numerical approaches we investigate how the spin texture of the electron eigenstates due to the interplay of spin-orbit coupling and inversion asymmetry determines the sign of the induced spin polarization as a function of the chemical potential or band filling, both in the absence and presence of local disorder. With the latter, we find that the induced spin polarization evolves from a non monotonous behavior at zero temperature to a monotonous one at higher temperature. Our results may provide a sound framework for the interpretation of recent experiments.