VERTICALLY MAGNETIZED FILM ELEMENT OF POLYCRYSTALLINE COBALT FERRITE AND MANUFACTURE THEREOF

摘要

PURPOSE:To obtain a Co ferrite magnetized film showing vertically magnetized characteristics irrespective of a polycrystal by using Co ferrite provided with a properly small spontaneous magnetizing MS and utilizing a stress based on difference between coefficients of thermal expansion of a substrate and the magnetized film. CONSTITUTION:Making a spontaneous magnetizing MS properly small can be achieved by substituting CO2+ in CoFe2O4 and/or Fe3+ with a proper metal ion. In other words, a ploycrystalline Co ferrite film shown by CO1-xFe2-yMx +yO4 [M is a metal ion except Fe3+, 0.5=(x+y)] is provided on a substrate. If, in this time, an amount of substitution (x+y) is smaller than 0.5, a vertically magnetized film can not be obtained because the spontaneous magnetizing MS is too large. However, since increase in an amount of substitution (x) of M ion for Co causes decrease in magneto-optical effect of the Co ferrite magnet ized film, it is preferable to make the amount of substitution zero by devising decrease in spontaneous magnetization with only an amount of substitution (y) for Fe. An amount of replacement (x) is used in the range of x=0.5.