Anisotropic magnetotransport in LaAlO$_3$/SrTiO$_3$ nanostructures

TL;DR

This study investigates how structural domain walls in SrTiO$_3$ influence the anisotropic magnetotransport properties of LaAlO$_3$/SrTiO$_3$ nanostructures, revealing random and temperature-dependent magnetoresistance behaviors.

Contribution

It demonstrates that domain wall orientations cause highly anisotropic and variable magnetoresistance in nanostructures, highlighting the role of structural phase transitions in transport properties.

Findings

Magnetoresistance varies randomly in magnitude and sign across nanostructures.

Warming above 105K significantly alters the magnetoresistance, even reversing its sign.

Domain wall orientation affects the overall magnetoresistance pattern.

Abstract

A number of recent studies indicate that the charge conduction of the LaAlO$_3$/SrTiO$_3$ interface at low temperature is confined to filaments which are linked to structural domain walls in the SrTiO$_3$ with drastic consequences for example for the temperature dependence of local transport properties. We demonstrate that as a consequences of this current carrying filaments on the nano-scale the magnetotransport properties of the interface are highly anisotropic. Our magnetoresistance measurements reveal that the magnetoresistance in different nanostructures ($<500nm$) is random in magnitude and sign, respectively. Warming up nanostructures above the structural phase transition temperature (105K) results in the significant change in MR. Even a sign change of the magnetoresistance is possible. The results suggest that domain walls that are differently oriented with respect to the surface exhibit different respective magnetoresistance and the total magnetoresistance is a result of a random domain wall pattern formed during the structural phase transition in the SrTiO$_3$ at cool down.