Crystallization of sputtered amorphous oxide films

Abstract

Amorphous oxide films with a composition of Bi2DyFe5O12 have been prepared by rf sputtering technique. The crystallization process was investigated using x-ray diffraction, differential thermal analysis, magnetic properties, magnetic resonance spectra, magneto-optical Faraday spectra, Raman spectra, and infrared reflection spectra. Amorphous oxide films exhibit very small magnetization and Faraday rotation at room temperature. At about 600 °C amorphous films crystallize to a garnet phase. With crystallization the magnetization and Faraday rotation increase rapidly. Raman and infrared spectra studies show the presence of tetrahedral sites in the amorphous films. As the annealing temperature increases, the peaks corresponding to octahedral and dodecahedral sites occur successively. It is of interest to note that amorphous oxide films containing Fe3+ ions show no magnetic resonance spectra at 71 and 300 K. The films annealed above crystallization temperature show a normal resonance spectrum. With increasing annealing temperature the linewidth decreases rapidly and the effective magnetization and anisotropy constant increase.