Oxygen vacancy induced re-entrant spin glass behavior in multiferroic ErMnO3 thin films

TL;DR

This study demonstrates that oxygen vacancies in hexagonal ErMnO3 thin films induce a re-entrant spin glass state at low temperatures, revealing complex magnetic interactions influenced by defect chemistry.

Contribution

It uncovers the role of oxygen vacancies in inducing re-entrant spin glass behavior in ErMnO3 thin films, a phenomenon not previously reported in this material.

Findings

Films show ferroelectricity and magnetic order at low T.

Spin glass behavior appears at lower T in films with oxygen vacancies.

Re-entrant spin glass results from competing magnetic interactions.

Abstract

Epitaxial thin films of hexagonal ErMnO3 fabricated on Pt(111)/Al2O3(0001) and YSZ(111) substrates exhibited both ferroelectric character and magnetic ordering at low temperatures. As the temperature was reduced, the ErMnO3 films first showed antiferromagnetism. At lower temperatures, the films deposited at lower oxygen partial pressures exhibited spin glass behavior. This re-entrant spin glass behavior was attributed to competition between an antiferromagnetic interaction in the hexagonal geometry and a ferromagnetic interaction caused by a change in Mn valence induced by excess electrons from the oxygen vacancies.