Dynamical Spin Susceptibility and Spin Waves in Ferromagnetic Dilute Alloys

Abstract

A general expression of the dynamical transverse spin susceptibility for ferromagnetic dilute alloys of transition metals is obtained in the ladder approximation by using the Wolff-Clogston model for dilute alloys and by taking into account exchange interactions among electrons in the host metal. The dispersion relation of spin waves is calculated from the pole of the dynamical transverse spin susceptibility by making use of the one-particle Green's function obtained in the Hartree-Fock approximation and by assuming that both impurity potential and the difference between intra-atomic Coulomb integrals in the impurity and host atoms are small. The values of exchange stiffness constants are estimated and compared with experimental data for dilute nickel alloys with iron, copper and palladium. The possibility of the appearance of a local spin wave mode is discussed.