Effects of Ti-doping on evolution of coexisting magnetic phases in BaFeO3-δ thin films at room temperature

Abstract

BaFeO3-δ (BFO) thin films are deposited on different MgO single-crystal substrates with (001), (110), and (111) structural orientations and investigated for the structural and magnetic properties. These films show weak ferromagnetism and magnetocrystalline anisotropy, where (111) axis is found to be hard-axis of magnetization. As Ti-doping should reduce oxygen deficiencies, we have studied the effects of Ti-doping on BFO/MgO (001) system. This doping of nonmagnetic Ti4+ ions (with 3d0 orbital) at Fe-site in BaFeO3-δ largely enhances the magnetization at room temperature. After oxygen annealing of the undoped and doped films deposited on MgO (001), the films show further alteration of magnetization and structure depending on Ti-doping. These films either show a pinched magnetic hysteresis at zero field or a larger coercivity, which was otherwise absent in the untreated thin films. Our results reveal that such changes in magnetic hystereses take place due to the magnetocrystalline anisotropy and/or coexisted soft and hard (or less soft) magnetic phases in annealed films. The annealing-induced hard magnetic phase gets completely suppressed by Ti-doping in BFO film. © 2014 AIP Publishing LLC.