Effect of oxygen deficiencies on magnetic properties of epitaxial grown BaFeO3 thin films on (100) SrTiO3 substrates

BaFeO₃ (BFO) epitaxial thin films on [001] SrTiO₃ substrates have been successfully produced by pulsed laser beam deposition. The epitaxially grown BFO was found to have tetragonal crystal structure with some amount of oxygen deficiencies. The magnetic susceptibilities of the samples strongly depended on the (hkl) directions of BFO varied in accordance with the crystalline directions, i.e., χ₍₁₀₀₎<χ_[110]<χ_[001]. The magnetic spin structure of the epitaxially grown BFO was speculated to be conventional antiferromagnetic. The remanent magnetization of the samples was found to depend on the amount of oxygen deficiencies significantly. This implies that the 180° superexchange interaction of Fe⁴⁺-O^2--Fe⁴⁺ may possibly produce some kinds of ferromagnetic ordering.