Magnetoresistance of 2D and 3D Electron Gas in LaAlO3/SrTiO3 Heterostructures: Influence of Magnetic Ordering, Interface Scattering and Dimensionality

TL;DR

This study compares magnetoresistance in LaAlO3/SrTiO3 interfaces with different dimensionalities, revealing how magnetic ordering, interface scattering, and electron transport dimensionality influence MR behavior and anisotropy.

Contribution

It demonstrates that magnetoresistance measurements can distinguish between 2D and 3D charge transport and identify various scattering mechanisms in LAO/STO heterostructures.

Findings

Low PO2 samples exhibit larger MR than high PO2 samples.

MR anisotropy is observed in both quasi-2D and 3D interfaces.

Out-of-plane magnetic field produces larger MR than in-plane field.

Abstract

Magnetoresistance (MR) anisotropy in LaAlO3/SrTiO3 (LAO/STO) interfaces is compared between samples prepared in high oxygen partial pressure (PO2) of 10-4 mbar exhibiting quasi-two-dimensional (quasi-2D) electron gas and low PO2 of 10-6 mbar exhibiting 3D conductivity. While MR of an order of magnitude larger was observed in low PO2 samples compared to those of high PO2 samples, large MR anisotropies were observed in both cases. The MR with the out-of-plane field is always larger compared to the MR with in-plane field suggesting lower dissipation of electrons from interface versus defect scattering. The quasi-2D interfaces show a negative MR at low temperatures while the 3D interfaces show positive MR for all temperatures. Furthermore, the angle relationship of MR anisotropy for these two different cases and temperature dependence of in-plane MR are also presented. Our study demonstrates that MR can be used to distinguish the dimensionality of the charge transport and various (defect, magnetic center, and interface boundary) scattering processes in this system.