Magnetic Properties of Fe₆₅(Ni_1-<i>x</i>Mn_<i>x</i>)₃₅ Alloys under Hydrostatic Pressure

Abstract

Magnetic measurements under hydrostatic pressure up to 8 kbar were made on f.c.c. Fe 65 (Ni 1- x Mn x ) 35 alloys in magnetic fields up to 12 kOe and at temperatures down to 4.2°K. The results indicate that in the ferromagnetic alloys ( x <0.3) the spontaneous magnetization and the Curie temperature decrease appreciably by compression and the fractional change of the spontaneous magnetization with pressure at low temperatures -σ -1 d σ/ d P is nearly equal to the fractional change of the Curie temperature with pressure - T c -1 d T c / d P and both values are approximately proportional to the high field susceptibility at low temperatures. These ferromagnetic volume effects can be understood in terms of weak itinerant electron ferromagnetism. On the other hand, the Néel temperature and the magnetic susceptibility of the antiferromagnetic alloys (0.3< x ) decrease by compression. These antiferromagnetic volume effects can qualitatively be explained by using a band theory of antiferromagnetism.