Conduction electron spin-flip scattering by impurities in copper

Abstract

We have measured the concentration dependence of the transmission conduction electron spin resonance linewidth of copper doped with Li, Zn, Ga, Ge, As, Ni, and Ti. In each case, we find a linear concentration dependence which allows us to determine a spin-flip cross-section, σsf, for each impurity. These cross-sections, together with those deduced from linewidth data previously published for other impurities (both magnetic and not), form a useful body of results and allow one to test spin-flip scattering models. We find an overall agreement of our values for σsf for transition metal impurities with estimates based on the Friedel virtual bound state model, including a spin-orbit interaction. For specific impurities (Zn, Ga, Ge, and As) we find that σ sf is determined by the charge contrast between the impurity and the copper host as was noted earlier from similar studies based on Li and Na by Asik, Ball, and Slichter. A particular situation is present with Li as an impurity in copper, interpreted as a « spin-orbit hole », which, together with the other results, confirm that the spin-orbit difference between the impurity and the host is the relevant spin-orbit parameter for σsf