Magnetic Properties under Pressure of Some Transition Metal Alloys

We have studied the variation of the Curie temperature θf and the spontaneous magnetization σs of several transition metals and some of their solid solutions as a function of the pressure. The measurements were carried out between 77° and 700°K. In the system Ni–Si, dθf/dp varies from 0.32×10−3 °K bar−1 for pure nickel to 0.05×10−3 °K bar−1 for Ni-9 at.% Si. The magnitude of dθf/dp decreases by 0.033×10−3 °K bar−1 per 1% of Si dissolved. In the system Ni–Cu, dθf/dp decreases by 0.01×10−3 °K bar−1 per 1% of Cu dissolved. For polycrystalline cobalt, (σl)−1 (∂σl/∂p), at 293°K, is equal to −10±1.5×10−7 bar−1. The molecular field coefficient, representing the exchange integrals, increases for a decrease in volume in the case of Fe, Ni, Co, and the solid solutions Ni–Si, Ni–Cu, Fe–Si. The relative variation of the spontaneous magnetization with pressure is accounted for by the use of band theory.