Spin texture driven spintronic enhancement at the LaAlO$_3$/SrTiO$_3$ interface

TL;DR

This paper provides a theoretical analysis of how spin-orbital textures and multi-orbital subband structures at LaAlO$_3$/SrTiO$_3$ interfaces influence spintronic responses, revealing mechanisms for enhancement and tunability with doping.

Contribution

It introduces a theoretical framework linking spin-orbital textures and subband structures to spintronic response enhancement at oxide interfaces.

Findings

Spin-orbital textures originate from broken inversion symmetry.

Interband effects cause non-monotonic response evolution.

Analytical models explain the response mechanisms.

Abstract

Recent experiments have shown that transition metal oxide heterostructures such as SrTiO$_3$-based interfaces, exhibit large, gate tunable, spintronic responses. Our theoretical study showcases key factors controlling the magnitude of the conversion, measured by the inverse Edelstein and Spin Hall effects, and their evolution with respect to an electrostatic doping. The origin of the response can be linked to spin-orbital textures. These stem from the broken inversion symmetry at the interface which produces an unusual form of the interfacial spin-orbit coupling, provided a bulk atomic spin-orbit contribution is present. The amplitudes and variations of these observables are direct consequences of the multi-orbital subband structure of these materials, featuring avoided and topological crossings. Interband contributions to the coefficients lead to enhanced responses and non-monotonic evolution with doping. We highlight these effects using analytical approaches and low energy modeling.