Oxygen-Vacancy-Induced Antiferromagnetism to Ferromagnetism Transformation in Multiferroic Thin Films

TL;DR

This study demonstrates how oxygen vacancies in Eu0.5Ba0.5TiO3-{ extdelta} thin films induce a transition from antiferromagnetic to ferromagnetic order, revealing a new method to control magnetic properties in multiferroic materials.

Contribution

It provides experimental and theoretical evidence that oxygen vacancies can switch magnetic order from antiferromagnetic to ferromagnetic in multiferroic thin films.

Findings

Oxygen vacancies increase in the thin films with different fabrication conditions.

Ferromagnetic behavior observed with a Curie temperature of 1.85 K.

Ti3+ ions from vacancies mediate ferromagnetic coupling.

Abstract

Oxygen vacancies (VOs) effects on magnetic ordering in Eu0.5Ba0.5TiO3-{\delta} (EBTO3-{\delta}) thin films have been investigated using a combination of experimental measurements and first-principles density-functional calculations. Two kinds of EBTO3-{\delta}thin films with different oxygen deficiency have been fabricated. A nuclear resonance backscattering spectrometry technique has been used to quantitatively measure contents of the VOs. Eu0.5Ba0.5TiO3 ceramics have been known to exhibit ferroelectric (FE) and G-type antiferromagnetic (AFM) properties. While, a ferromagnetic (FM) behavior with a Curie temperature of 1.85 K has been found in the EBTO3-{\delta} thin films. Spin-polarized Ti3+ ions, which originated from the VOs, has been proven to mediate a FM coupling between the local Eu 4f spins and were believed to be responsible for the great change of the magnetic ordering. Our work opens up a new avenue for developing FM-FE materials by manipulating the oxygen deficiency in AFM-FE multiferroics.