Effects of spin-orbit interaction upon impurity scattering in dilute alloys

An earlier treatment of impurity scattering in dilute noble-metal alloys based on exact solutions of the Schr\"odinger equation for a lattice of muffin-tin potentials, is extended to take into account relativistic effects. For a nonrelativistic impurity in a relativistic host, the effects of spin-orbit interaction upon the host Fermi surface and impurity-induced Dingle-temperature anisotropies are calculated. Experimental Dingle-temperature anisotropies of Au(Cu), Au(Zn), and Au(Ag) are analyzed to yield phase shifts that describe scattering of conduction electrons at the Fermi level by the impurity atoms. For a relativistic impurity in a nonrelativistic host, Dingle-temperature anisotropies and spin-flip relaxation rates for conduction-electron spin resonance are discussed. A model calculation shows that host-lattice backscattering effects contribute significantly to the spin-flip scattering time T₁. Dingle-temperature anisotropies and spin-flip relaxation rates for Cu(Ge) and Cu(Au) are analyzed to yield the spin-orbit parameters of the impurity atoms in these alloys.