Muon Depolarization by Paramagnetic Impurities in Nonmagnetic Metals

Abstract

The range of metals and temperatures for which positive muon diffusion is measurable can be expanded greatly by doping nonmagnetic metals with paramagnetic ions. In these systems, the diffusivity determines the time needed for the ${\ensuremath{\mu}}^{+}$ to reach the sites of strong depolarization near the paramagnetic ions and hence the depolarization rate of the muon spin rotation signal. For $\mathrm{Au}\mathrm{Gd}$ and $\mathrm{Au}\mathrm{Er}$ we have measured diffusion-induced depolarization for temperatures between 85 and 230 K, and have determined that there is an important short-range component in the muon-ion interaction.