Defect engineering of magnetic ground state in EuTiO$_3$ epitaxial thin films

TL;DR

This study demonstrates how atomistic defect engineering in EuTiO3 thin films can controllably switch their magnetic ground state from antiferromagnetic to ferromagnetic by manipulating Eu-O vacancies, revealing insights into their electronic and magnetic interactions.

Contribution

The paper introduces a systematic defect engineering approach to control the magnetic phase in EuTiO3 epitaxial thin films, linking defect-induced structural changes to magnetic and electronic properties.

Findings

Eu-O vacancies induce a transition from antiferromagnetic to ferromagnetic phase.

The electronic structure change is due to weakened Eu-Ti-Eu super-exchange interaction.

Defect engineering enables tailored magnetic ground states in EuTiO3 thin films.

Abstract

Atomistic defect engineering through the pulsed laser epitaxy of perovskite transition metal oxides offers facile control of their emergent opto-electromagnetic and energy properties. Among the various perovskite oxides, EuTiO3 exhibits a strong coupling between the lattice, electronic, and magnetic degrees of freedom. This coupling is highly susceptible to atomistic defects. In this study, we investigated the magnetic phase of EuTiO$_3$ epitaxial thin films via systematic defect engineering. A magnetic phase transition from an antiferromagnet to a ferromagnet was observed when the unit cell volume of EuTiO3 expanded due to the introduction of Eu-O vacancies. Optical spectroscopy and density functional theory calculations show that the change in the electronic structure as the ferromagnetic phase emerges can be attributed to the weakened Eu-Ti-Eu super-exchange interaction and the developed ferromagnetic Eu-O-Eu interaction. Facile defect engineering in EuTiO$_3$ thin films facilitates understanding and tailoring of their magnetic ground state.