Investigation of the tunnel magnetoresistance in junctions with a strontium stannate barrier

TL;DR

This study explores the magnetic and electrical properties of La$_{0.67}$Sr$_{0.33}$MnO$_{3}$ junctions with SrSnO$_3$ barriers, revealing significant tunnel magnetoresistance despite defects, and highlights potential improvements with better lattice matching.

Contribution

It demonstrates that SrSnO$_3$ barriers can achieve high TMR in magnetic tunnel junctions despite lattice mismatch and defects, suggesting pathways for further enhancement.

Findings

TMR reaches up to 350% at 5 K

TMR decreases with increasing bias voltage

TMR vanishes above 200 K

Abstract

We experimentally investigate the structural, magnetic and electrical transport properties of La$_{0.67}$Sr$_{0.33}$MnO$_{3}$ based magnetic tunnel junctions with a SrSnO$_3$ barrier. Our results show that despite the large number of defects in the strontium stannate barrier, due to the large lattice mismatch, the observed tunnel magnetoresistance is comparable to tunnel junctions with a better lattice matched STiO$_3$ barrier, reaching values of up to 350% at T=5 K. Further analysis of the current-voltage characteristics of the junction and the bias voltage dependence of the observed tunnel magnetoresistance show a decrease of the TMR with increasing bias voltage. In addition, the observed TMR vanishes for T>200 K. Our results suggest that by employing a better lattice matched ferromagnetic electrode and thus reducing the structural defects in the strontium stannate barrier even larger TMR ratios might be possible in the future.