Depth-resolved profile of the interfacial ferromagnetism in $CaMnO_{3}/CaRuO_{3}$ superlattices

TL;DR

This study reveals that interfacial ferromagnetism in CaMnO3/CaRuO3 superlattices extends beyond the interface into multiple layers, driven by charge transfer and defect chemistry, challenging previous models and opening avenues for magnetic property manipulation.

Contribution

It provides the first detailed depth-resolved profile of interfacial ferromagnetism in these superlattices, highlighting the role of charge transfer and oxygen vacancies in magnetic behavior.

Findings

Ferromagnetism extends beyond the interface into multiple CaMnO3 layers.

Asymmetry in magnetic profile is influenced by oxygen vacancies.

Double exchange mechanism driven by charge transfer explains ferromagnetism.

Abstract

Emergent magnetic phenomena at interfaces represent a frontier in materials science, pivotal for advancing technologies in spintronics and magnetic storage. In this letter, we utilize a suite of advanced X-ray spectroscopic and scattering techniques to investigate emergent interfacial ferromagnetism in oxide superlattices comprised of antiferromagnetic CaMnO3 and paramagnetic CaRuO3. Our findings challenge prior theoretical models by demonstrating that the ferromagnetism extends beyond the interfacial layer into multiple unit cells of CaMnO3 and exhibits an asymmetric profile. Complementary density functional calculations reveal that the interfacial ferromagnetism is driven by the double exchange mechanism, facilitated by charge transfer from Ru to Mn ions. Additionally, defect chemistry, particularly the presence of oxygen vacancies, likely plays a crucial role in modifying the magnetic moments at the interface, leading to the observed asymmetry between the top and bottom CaMnO3 interfacial magnetic layers. Our findings underscore the potential of manipulating interfacial ferromagnetism through point defect engineering.