DEPTH-DEPENDENT LATTICE-PARAMETER VARIATION AND STRESS-INDUCED MAGNETIC-ANISOTROPY OF ULTRATHIN DY2BIFE4GAO12 GARNET-FILMS DEPOSITED ON THEGLASS SUBSTRATE BY PYROLYSIS

Lattice parameter variation as a function of depth from the free surfa ce of ultrathin Dy2BiFe4GaO12 garnet films for magneto-optic applicati on has been investigated. These thin films were synthesized by pyrolys is on the glass substrate and annealed at 660-degrees-C in the glass t ransition range. The lattice parameters were determined by grazing inc idence x-ray in asymmetric Bragg diffraction. X-ray diffraction result s show that film stress is compressively greater near the glass/film i nterface and becomes smaller in magnitude toward the free-film surface . This observation has been interpreted as a result of softening of th e glass substrate during annealing in the glass transition range and t he subsequent larger shrinkage of the glass substrate with respect to the deposited crystalline film upon cooling. The thermal expansion dif ference between the substrate and the deposited film can in tum cause the stress-induced magnetic anisotropy. The induced magnetic anisotrop y factor K(u) has the maximum value above a threshold film thickness, about 600 angstrom. Down to this limit, K(u) increases with the decrea sing film thickness.