Positive exchange bias in ferromagnetic La0.67Sr0.33MnO3 / SrRuO3 bilayers

TL;DR

This study demonstrates positive exchange bias in epitaxial La0.67Sr0.33MnO3/SrRuO3 bilayers, showing temperature-dependent interfacial magnetic coupling likely caused by atomic layer charge transfer.

Contribution

It reveals positive exchange bias in ferromagnetic bilayers and proposes atomic layer charge transfer as the mechanism for interfacial exchange coupling.

Findings

Positive exchange bias observed below SRO Curie temperature

Bias magnitude increases as temperature decreases

Interfacial charge transfer influences magnetic coupling

Abstract

Epitaxial La0.67Sr0.33MnO3 (LSMO)/ SrRuO3 (SRO) ferromagnetic bilayers have been grown on (001) SrTiO3 (STO) substrates by pulsed laser deposition with atomic layer control. We observe a shift in the magnetic hysteresis loop of the LSMO layer in the same direction as the applied biasing field (positive exchange bias). The effect is not present above the Curie temperature of the SRO layer (), and its magnitude increases rapidly as the temperature is lowered below . The direction of the shift is consistent with an antiferromagnetic exchange coupling between the ferromagnetic LSMO layer and the ferromagnetic SRO layer. We propose that atomic layer charge transfer modifies the electronic state at the interface, resulting in the observed antiferromagnetic interfacial exchange coupling.