Tunable spin and orbital Edelstein effect at (111) LaAlO$_3$/SrTiO$_3$ interface

TL;DR

This paper predicts a significantly larger orbital Edelstein effect compared to the spin one at the (111) LaAlO3/SrTiO3 interface, utilizing a tight-binding model and Boltzmann transport theory to analyze the phenomena.

Contribution

It introduces a theoretical prediction of an orbital Edelstein effect that surpasses the spin Edelstein effect at the oxide interface, highlighting the role of band hybridization.

Findings

Orbital Edelstein effect is an order of magnitude larger than spin Edelstein effect.

Hybridization between electronic bands critically influences Edelstein susceptibility.

Effective low-filling model explains non-trivial Edelstein response behavior.

Abstract

Converting charge current into spin current is one of the main mechanisms exploited in spintronics. One prominent example is the Edelstein effect, namely the generation of a magnetization in response to an external electric field, which can be realized in systems with lack of inversion symmetry. If a system has electrons with an orbital angular momentum character, an orbital magnetization can be generated by the applied electric field giving rise to the so-called orbital Edelstein effect. Oxide heterostructures are the ideal platform for these effects due to the strong spin-orbit coupling and the lack of inversion symmetries. Beyond a gate-tunable spin Edelstein effect, we predict an orbital Edelstein effect an order of magnitude larger then the spin one at the (111) LaAlO$_3$/SrTiO$_3$ interface. We model the material as a bilayer of $t_{2g}$ orbitals using a tight-binding approach, while transport properties are obtained in the Boltzmann approach. We give an effective model at low filling which explains the non-trivial behaviour of the Edelstein response, showing that the hybridization between the electronic bands crucially impacts the Edelstein susceptibility.