On the origin of magnetoresistance in Sr$_2$FeMoO$_6$

TL;DR

This study investigates the magnetoresistance in Sr$_2$FeMoO$_6$, revealing that grain boundary magnetic polarization, not the grains themselves, primarily controls the magnetoresistance through a resonant tunnelling mechanism.

Contribution

It demonstrates that magnetoresistance in Sr$_2$FeMoO$_6$ is governed by grain boundary magnetic polarization, providing new insights into the material's electronic transport properties.

Findings

Magnetoresistance switches with magnetization.

Magnetoresistance is controlled by grain boundary regions.

Resonant tunnelling mechanism explains the behavior.

Abstract

We report detailed magnetization ($M$) and magnetoresistance ($MR$) studies on a series of Sr$_2$FeMoO$_6$ samples with independent control on anti-site defect and grain boundary densities. These results, exhibiting a switching-like behavior of $MR$ with $M$, establish that the $MR$ is controlled by the magnetic polarization of grain boundary regions, rather than of the grains within a resonant tunnelling mechanism.