Dynamic Susceptibilities of Transition Metal Alloys

Abstract

In this paper, we study dynamical properties of transition metal alloys by examining the form of the frequency and wavevector-dependent magnetic susceptibility within the framework of a simple molecular-field approximation. We describe the metal by a simple one-band model, in which two d electrons in the atomic cell i interact via the intra-atomic Coulomb interaction Ui, which differs from the value in the host if i refers to an impurity site. The impurity also is supposed to produce a local change in crystal potential. In the general case, an expression for the susceptibility is derived in the form of an N×N matrix, where N is the number of lattice sites. When applied to a pure metal, the result reduces to the expression obtained previously by Izuyama, Kim, and Kubo. Some applications of the results to the one-impurity problem are considered. In particular, in the case where a magnetic moment has formed in the impurity cell, a description of the electron spin-resonance of the impurity center is obtained. A discussion of properties of Pd-Ni alloys is presented. The expression obtained for the magnetic susceptibility allows a calculation of the contribution to the electrical resistivity from s-d spin flip scattering. The recent resistivity measurements of Schindler and Rice are interpreted with the results.