PURPOSE: To assure substantially magnetooptic characteristics and to prevent the oxidation of a thin rare earth transition metal alloy film by constituting said film in such a manner that the refractive index of the 1st transparent dielectric film made of the same nitride is larger than the refractive index of the 2nd transparent dielectric film.
CONSTITUTION: A transparent AlN film 7 which is the 1st transparent dielectric film, a thin GdTbFe alloy film 3 which is the thin rare earth transition metal alloy film, a transparent AlN film 8 which is the 2nd transparent dielectric film and an Al film 9 which is a reflecting film are formed on a transparent substrate. The AlN film having the high refractive index is used as the 1st transparent film and the AlN film having the low refractive index is used as the 2nd transparent dielectric film. The effect of increasing Kerr rotating angle is obtd. by the 1st transparent dielectric film having the large refractive index. On the other hand, the reflectivity can be increased by the 2nd transparent dielectric film having the small refractive index. The AlN does not contain oxygen as the component thereof and therefore the danger that the thin rare earth transition metal alloy film is oxidized is considerably decreased.
MURAKAMI YOSHITERU
HIROKANE JIYUNJI
KATAYAMA HIROYUKI
OOTA KENJI
YAMAOKA HIDEYOSHI
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