Shaping the Magnetic Properties of BaFeO₃ Perovskite-Type by Alkaline-Earth Doping

The alkaline-earth iron perovskites AFeO₃ are interesting materials since their ferromagnetic domains could be controlled by an applied magnetic field. However, to be exploited for applications, there are still some flaws related to their antiferromagnetic or ferromagnetic behavior at low temperatures. In our work, we have attempted to synthesize pristine BaFeO₃ with Ba to partially or fully substitute Sr or Ca in order to tailor the magnetic properties of the host compound as expected for applications. We found that powders of (Ca/Sr/Ba) FeO₃ showed an increased enhancement of magnetic properties in comparison to BaFeO₃ films. In particular, the (Ca/Sr)_0.5Ba_0.5FeO₃ nanopowders have demonstrated a Curie temperature well above room temperature along with an increased magnetic moment. A considerable coercivity is also surprisingly obtained as a typical signature for a hard magnetic material. First-principles calculations were performed to get an insight into the Ca/Sr influence on the lattice structure, and oxygen vacancies behavior of Ba_xCa(Sr)_1-xFeO₃. It was found that doping can lead to an increase of the magnetic moment per Fe atom. However, Ca/Sr-site substitution at the Ba-site of the perovskite exhibits an increasing of magnetic moment per Fe when O vacancies are introduced. This current study shows a new way to exploit this revisited-type of orthoferrites for spintronic applications.