Study of magnetization and crystallization in sputter deposited LiZn ferrite thin films

LiZn ferrite films of composition LiO0.5-x/2Mn0.1ZnxFe2.35-x/2O4 with x = 0.32 were rf sputter deposited on fused quartz substrates at ambient temperature. The as-deposited films were found by x-ray diffraction to be amorphous but magnetic, and showed large high field susceptibility. The films were studied after they were annealed at various temperatures up to 850 degrees C. It was observed that the films crystallize upon annealing and the value of the saturation magnetization increases with annealing temperature. The high field susceptibility, on the other hand, decreases with increasing anneal temperature. The measured ferromagnetic resonance spectra of these films indicated that the films consist of at least two different magnetic materials. A significant portion in the film crystallizes and the value of saturation magnetization of this portion tends to the bulk value as annealing temperature is increased. However, a small portion of the film remains in a highly defective state all through, even up to annealing temperatures of 850 degrees C. The high field susceptibility data indicates that point defects could play an important role in determining the magnetic properties of these films. (C) 1999 American Institute of Physics. [S0021-8979(99)07018-8].