Magnetic Studies of Pristine, Rare-Earth, and Alkaline-Earth- Doped BaFeO3-δ

Abstract

Abstract

Magnetic Studies of Pristine, Rare-Earth, and Alkaline-Earth- Doped BaFeO3-δ

Jang Gun Kim Dept. of Physics and Astronomy The Graduate School Seoul National University

BaFeO3-δ (BFOδ) is a potential candidate for bubble domain devices that may have fast and high-capacity data storage. The stoichiometric BaFeO3 is ferromagnetic, however, its Tc is low (111K). Thus, it is meaningful to improve the magnetic properties of oxygen deficient BFOδ with higher transition temperature. In this work, we studied magnetic properties of the polycrystalline powders and thin films of undoped, half-doped BFOδ fabricated by coprecipitation method and pulsed laser deposition, respectively. BFOδ itself shows room temperature ferromagnetism possibly induced by the decrease in its grain size. In general, Rare-Earth (Ho3+, Sm3+) doping does not improve the magnetic properties of BFOδ due to the introduction of Fe3+ by trivalent Rare Earth ions, leading to antiferromagnetic superexchange interaction. The magnetizations of SmFeO3 and Ba0.5Ho0.5FeO3-δ films, however, show strong responses to perpendicular field. Powders doped with Alkaline-Earth (Ca2+, Sr2+) ions still maintain their room temperature ferromagnetism and have a larger magnetization when comparing to Rare-Earth doped ones. Moreover, Sr doping can turn BFOδ into a hard magnet.