Microstructure of Bi1.5Y1.5Fe5O12 Films Made by Pyrolysis

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Abstract
Bi-substituted iron garnet films 0.06 µm ∼0.06 µm in thickness (t) were made by prolysis. They were subjected to SEM and optical microscopic observations of microstructures. Starting around 600°C, the crystallization of the films proceeded to 60°C. Crystalline Crystalline grains 1 µm ∼ 2 µm in diameter were observed. A considerable amount of amorphous phase remained in thinner (t< 0.3 µm) films even after they were annealed above 660°C for a sufficient time. The saturation magnetization and Faraday rotation of the films thinner than 0.3 µm were considerably smaller than those in bulk samples, which might be ascribed to the amorphous phase. The thinner the film, the larger the amount of amorphous phase remaining, because surface free energy (which obstructs crystalline grain growth) increased as the film thickness decreased.