Spontaneous Volume Magnetostiction of Fe₆₅ (Ni1-xMnx)₃₅ Alloys

Thermal expansion measurements were made on f.c.c. Fe 65 (Ni 1- x Mn x ) 35 alloys at temperatures down to 4.2°K and the spontaneous volume magnetostriction of these alloys was evaluated from their thermal expansion curves. The results indicate that the spontaneous volume magnetostriction at 0°K is positive and decreases with increasing x in the ferromagnetic alloys ( x <0.3), and is positive and increases with increasing x in the antiferromagnetic alloys (0.3< x ). The spontaneous volume magnetostriction varies with temperature as T 2 in the temperature range below about half of the magnetic transition temperature. If a simple and reasonable density of states curve is assumed, these experimental results can be understood on the basis of the weak itinerant electron ferromagnetism or of the weak itinerant electron antiferromagnetism.