Magnetic order and valency at La$_{0.7}$Sr$_{0.3}$MnO$_{3}$/SrTiO$_{3}$ interfaces

TL;DR

This study uses first principles calculations to analyze how different interface terminations in La$_{0.7}$Sr$_{0.3}$MnO$_{3}$/SrTiO$_{3}$ affect magnetic order and valency, revealing how interface engineering can control magnetic properties.

Contribution

It demonstrates how interface termination types influence magnetic coupling and how inserting LaMnO$_{3}$ layers can restore ferromagnetism at the interface.

Findings

La$_{0.7}$Sr$_{0.3}$O/TiO$_{2}$ interface maintains ferromagnetic coupling.

MnO$_{2}$/SrO interface favors antiferromagnetic coupling.

Inserting LaMnO$_{3}$ layers recovers ferromagnetism.

Abstract

We report on first principles calculations of the electronic structure of La$_{0.7}$Sr$_{0.3}$MnO$_{3}$/SrTiO$_{3}$ junction with two possible types of interface terminations. We find that the La$_{0.7}$Sr$_{0.3}$O/TiO$_{2}$ interface preserves the interlayer ferromagnetic coupling between the interface MnO$_{2}$ layer and the bulk. The other interface, MnO$_{2}$/SrO, favours antiferromagnetic coupling with the bulk. By inserting two unit cells of undoped LaMnO$_{3}$ at the interface the ferromagnetism is recovered. This is understood in terms of the doping level and the mobility of carriers near the interface.