EFFECT OF PRESSURE ON THE CURIE TEMPERATURE OF RARE-EARTH METALS. I. GADOLINIUM

An experimental investigation was undertaken for the purpose of learning the effect of interatomic distance on the magnetic exchange interaction of ferromagnetic rare-earth metals. The first material studied is gadolinium. A toroidal-shaped specimen of gadolinium was subjected to pressures up to about 40 kbar. The gadolinium toroid served as a transformer core. A constant input voltage was applied and the output voltage was studied as a function of pressure and temperature. The Curie temperature, obtained from the output voltage, was found to be depressed linearly with pressure at a rate of --1.60 deg C/(kbar) up to 21.5 kbar. Between 21.5 and 26.7 kbar a phase transition to a nonferromagnetic state occurred. (auth)