Magnetostriction of Paramagnetic Transition Metals. II. Group-VIII Metals Ru, Rh, Pd, Ir, Pt, and Their Alloys
The longitudinal magnetostriction of group-VIII transition metals and alloys was measured with a capacitance dilatometer at 4.2 °K in fields up to 100 kOe. The resultant values of the logarithmic volume dependence of the magnetic susceptibility, ∂lnχ∂lnV, are Ru, -4.8; Rh, 9.6; Pd, -3.4; Ir, 22; Pt, -15; Rh50Ir50, 15; Rh50Pd50, 8; Ir40Pd40, 14; Pd67Pt33, -4; and Pd33Pt67, -24. Pd, Pt, and their alloys have a negative magnetostriction, which indicates a negative volume dependence of the Coulomb interaction responsible for the exchange enhancement of their spin susceptibility. Rh, Ir, and their alloys with each other and with Pd have a positive magnetostriction, and the resultant large volume dependence of the susceptibility, particularly that of Ir, is difficult to understand. Float-zoned samples of Rh and Ir exhibit oscillatory de Haas-van Alphen magnetostriction at 4.2 °K.