Muon diffusion and relaxation in YCo 2

Abstract

Muons were expected to gain additional information about the spin fluctuations proposed for this enhanced paramagnetic system. At the lowest temperatures the μ +SR signal can be explained by a static Kubo–Toyabe relaxation function. On raising the temperature an interplay is suggested to occur between muon diffusion and electronic relaxation of “Co-clusters” surrounding a Co vacancy yielding a maximum in the fluctuation rate versus temperature curve. This behaviour is similar to that found in the case of paramagnetic impurities in nonmagnetic metals, the “Co-cluster” moment being the analogue to the impurity spin.