WET-PROCESS PREPARATION OF AMORPHOUS Y-FE OXIDE-FILMS FERROMAGNETIC AT ROOM-TEMPERATURE

Yttrium iron ferrite films of amorphous structure (as examined by x-ray diffraction), having ferromagnetic moment at room temperature, are successfully synthesized from an aqueous solution by a ferrite plating method in which the substrate is heated by Xe-lamp beams. The atomic ratio of Y/Fe in the films is adjusted to Y/Fe=0.6, as in Y3Fe5O12, by properly choosing the atomic ratio (Y/Fe=3.5) in the reaction solution. The magnetization of the films at room temperature is 10-40 emu/cc, several times smaller than that observed for crystalline YIG. It exhibited, however, a paramagnetic Mossbauer spectrum at room temperature, suggesting that the weak magnetization is ascribed to the magnetic impurity phase whose concentration is too small to be discerned by x-ray diffraction and Mossbauer measurements. The spectrum has an isomer shift of 0.22 mm/sec at 300 K and a hyperfine field splitting of 462 kOe at 12 K, indicating that the Fe ions are in a trivalent high spin state.