The mechanism of spin-orbit coupling in a 2D oxide interface

TL;DR

This paper investigates the spin-orbit coupling mechanism in LaAlO₃/SrTiO₃ 2D interfaces, revealing a cubic Dresselhaus-like splitting and clarifying the origin of magnetoresistance through high-pressure transport analysis.

Contribution

It demonstrates that the spin-orbit coupling in this system is cubic and band-structure linked, and isolates multi-band effects using high-pressure transport measurements.

Findings

Magnetoresistance is due to quantum interference, not Coulomb interaction.

Spin-orbit coupling is cubic (Dresselhaus-like), not linear (Rashba-like).

High-pressure transport isolates multi-band contributions.

Abstract

The presence of spin-orbit coupling drives the anomalous magnetotransport at oxide interfaces and forms the basis for numerous intriguing properties of these 2D electron systems, such as topologically protected phases or anti-localization. For many of those systems, the identification of the underlying coupling mechanism is obfuscated by multi-band effects. We therefore analyze the transport of LaAlO$_3$/SrTiO$_3$ interfaces under high pressures, a technique to single out the multi-band contributions. We argue that the observed magnetoresistance is due to quantum interference and not related to Coulomb interaction. Therefore, this system is an excellent candidate to generate a metal-insulator transition of the long-sought symplectic 2D universality class. It is shown that the spin-orbit coupling can be linked unambiguously to the band structure with a cubic (Dresselhaus-like) rather than a linear (Rashba-like) spin-orbit band splitting.