Dynamic Susceptibilities of Transition Metal Alloys

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 $U_i$ , 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 $\mathrm{N\times N}$ 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.