A CALCULATION OF THE TEMPERATURE-DEPENDENT SUSCEPTIBILITY OF PD AND DILUTE PD1-XAGX AND PDHX ALLOYS

The temperature dependence of the magnetic properties of itinerant ele ctron systems is mainly due to the excitation of spin fluctuations. We calculate the susceptibilities of Pd, Pd1-xAgx, and PdH(x) (0 less-th an-or-equal-to x less-than-or-equal-to 0.03) with an extension of the classical Murata-Doniach model for spin fluctuations, which treats the energy functional without a Landau expansion of the magnetization-dep endent ground state energy. To obtain this energy ASW (augmented spher ical wave) and KKR-CPA bandstructure calculations are performed. In ag reement with experiment the KKR-CPA method yields a maximum of chi(T) for Pd, which disappears with increasing Ag concentration. In the Asw calculations, low Ag and H concentrations are simulated by the superce lls Pd31Ag and Pd32H. In addition the alloy PdH(x) is simulated by cal culations for pure Pd, with the valence electron concentration increas ed suitably. Calculations of the susceptibility of Pd within the frame work of the Stoner theory and the spin fluctuation theory based upon t he rigid-band model are presented. The role of the electron interactio n in both theories is examined and the reason for the maximum of chi(T ) for Pd is investigated. We find the different scaling of the tempera ture axis in the Stoner and spin fluctuation theories to have its orig in in a different treatment of the electron interaction.