Oxygen-Vacancy-Induced Antiferromagnetism to Ferromagnetism Transformation in Eu(0.5)Ba(0.5)TiO(3−δ) Multiferroic Thin Films

Oxygen vacancies (V(O)) effects on magnetic ordering in Eu(0.5)Ba(0.5)TiO(3−δ) (EBTO(3−δ)) thin films have been investigated using a combination of experimental measurements and first-principles density-functional calculations. Two kinds of EBTO(3−δ) thin films with different oxygen deficiency have been fabricated. A nuclear resonance backscattering spectrometry technique has been used to quantitatively measure contents of the V(O). Eu(0.5)Ba(0.5)TiO(3) 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 EBTO(3−δ) thin films. Spin-polarized Ti(3+) ions, which originated from the V(O), 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. Considering the easy formation of V(O), our work opens up a new avenue for achieving co-existence of FM and FE orders in oxide materials.