Influence of oxygen vacancies and La^sub 0.7^Sr^sub 0.3^MnO^sub 3^ layer on the structure and magnetic properties of cobalt ferrite thin films

CoFe2O4 thin film is expected to be used as the spin filter in spintronics. In order to prepare high-quality CoFe2O4 thin films for spin filtering, we studied the influence of oxygen vacancies on the structure and magnetic properties of cobalt ferrite (Co1−xFe2+xO4, CFO) films prepared in different atmosphere, and obtained the CFO films without significant soft magnetic phase under optimum Ar and O2 atmosphere condition. We further investigated the magnetic properties of the CFO/La0.7Sr0.3MnO3 (CFO/LSMO) bilayers containing various thicknesses of CFO films, and found that the CFO/LSMO bilayers with the ultrathin CFO films primarily display the soft magnetic properties.