Thermal expansion anomaly in amorphous YFe spin glasses

Abstract

The thermal expansion anomaly in amorphous Y 100− x Fe x (70 ⩽ x ⩽ 92.5) alloys has been measured with a differential transformer-type dilatometer. A large thermal expansion anomaly is observed in spite of the absence of ferromagnetism, and its magnitude is as large as that of amorphous LuFe alloys which exhibit a re-entrant spin-glass behavior. This clearly indicates that the magnetovolume effect is not necessarily correlated with the appearance of ferromagnetism. The large negative electronic contribution to the thermal expansion coefficient of amorphous YFe alloys is similar to that of Fe-based FeNi alloys. Such a characteristic property is explained by taking into account the amplitude of the local moment.