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; Rh₅₀{Ir}₅₀$, 15; ${Rh}₅₀Pd₅₀, 8; Ir₄₀{Pd}₄₀$, 14; ${Pd}₆₇Pt₃₃, -4; and Pd₃₃{Pt}₆₇$, -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.