Amorphous Magnetic Insulators for Microwave Device Applications

Results of our studies on thin films of amorphous magnetic oxides are summarized in this report. The main emphasis of the program was on the preparation and magnetic characterization of amorphous BiFeO3 films substituted with nonmagnetic perovskites, zinc ferrite, copper ferrite and calcium ferrite. Magnetization and ferromagnetic resonance techniques were used to study the magnetic structure in as-sputtered films, the onset of a magnetically ordered state in annealed samples, and the effects of crystallization on magnetic parameters. The main accomplishments of our efforts are 1 amorphous insulators with the highest saturation magnetization ever achieved were synthesized, 2 anisotropic amorphous magnets were realized in perovskite- spinel systems and 3 the nature and composition of magnetically ordered clusters that give rise to a spontaneous magnetic moment were identified in some compounds.