Effects of Cr2O3 or Y2O3 doping in barium ferrite thin-film medium for high-density recording

The effects of Cr2O3 or Y2O3 doping on the surface morphology and magnetic properties in barium ferrite thin films have been studied. Thin films were deposited by co-sputtering a barium ferrite target with a Cr2O3 or Y2O3 target. The deposited amorphous films were homogenized at a temperature of 600 degrees C for over 10 h followed by annealing at 800 degrees C in a tube furnace. It was observed that, whereas stoichiometric barium ferrite shows 5000 Angstrom x500 Angstrom acicular grainlike features, films doped with Cr2O3 or Y2O3 had equiaxed topographic features with an average size of 500 Angstrom. Magnetic studies showed that the coercivity of the doped films was over 3500 Oe and was larger than that of stoichiometric films. A weak magnetostatic interaction was found in all the films. Studies of the magnetic after effect indicated excellent thermal stability in all the films. (C) 1996 American Institute of Physics.