Giant negative magnetoresistance driven by spin-orbit coupling at the LAO/STO interface

TL;DR

This study investigates giant negative magnetoresistance at the LAO/STO interface, attributing it to spin-orbit coupling and impurity scattering, challenging previous Kondo-based explanations and highlighting a single-particle mechanism.

Contribution

The paper proposes a semiclassical Boltzmann transport model incorporating spin-orbit coupling and impurity scattering to explain magnetoresistance phenomena at the LAO/STO interface.

Findings

Magnetoresistance persists up to 20 K, indicating a single-particle mechanism.

Spin-orbit coupling combined with impurity scattering explains the observed effects.

The model accounts for the temperature and electron density dependence of magnetoresistance.

Abstract

The LAO/STO interface hosts a two-dimensional electron system that is unusually sensitive to the application of an in-plane magnetic field. Low-temperature experiments have revealed a giant negative magnetoresistance (dropping by 70\%), attributed to a magnetic-field induced transition between interacting phases of conduction electrons with Kondo-screened magnetic impurities. Here we report on experiments over a broad temperature range, showing the persistence of the magnetoresistance up to the 20~K range --- indicative of a single-particle mechanism. Motivated by a striking correspondence between the temperature and carrier density dependence of our magnetoresistance measurements we propose an alternative explanation. Working in the framework of semiclassical Boltzmann transport theory we demonstrate that the combination of spin-orbit coupling and scattering from finite-range impurities can explain the observed magnitude of the negative magnetoresistance, as well as the temperature and electron density dependence.