Spin responses and effective Hamiltonian for the two dimensional electron gas at oxide interface {LaAlO}$_3$/{SrTiO}$_3$

TL;DR

This paper derives an effective Hamiltonian for the 2DEG at LaAlO3/SrTiO3 interfaces, revealing anisotropic Rashba spin-orbit coupling that influences spin responses and can help identify the SOC's nature experimentally.

Contribution

It introduces a novel anisotropic Rashba SOC model for the 2DEG at oxide interfaces, highlighting orbital-specific effects and their impact on spin susceptibilities and spin Hall conductivity.

Findings

Anisotropic Rashba SOC differs for $d_{xz}$ and $d_{yz}$ orbitals.

Spin susceptibilities are anisotropic due to the SOC.

Spin Hall conductivity exhibits distinctive behavior influenced by the anisotropic SOC.

Abstract

Strong Rashba spin-orbit coupling (SOC) of the two-dimensional electron gas (2DEG) at the oxide interface $\mathrm{LaAlO_{3}/SrTiO_{3}}$ underlies a variety of exotic physics, but its nature is still under debate. We derive an effective Hamiltonian for the 2DEG at the oxide interface $\mathrm{LaAlO_{3}/SrTiO_{3}}$ and find a different anisotropic Rashba SOC for the $d_{xz}$ and $d_{yz}$ orbitals. This anisotropic Rashba SOC leads to anisotropic static spin susceptibilities and also distinctive behavior of the spin Hall conductivity. These unique spin responses may be used to determine the nature of the Rashba SOC experimentally and shed light on the orbital origin of the 2DEG.