Summary of Mössbauer evidence associated with the Kondo effect

Mössbauer-effect measurements provided the first direct evidence of the reduction of individual effective localized moments on magnetic impurities with decreasing temperature. While other techniques such as magnetic susceptibility measure static collective properties, the Mössbauer and nuclear-magnetic-resonance techniques enjoy the capability of directly measuring the spin polarization within atomic dimensions of a given nucleus on a time scale of $\tau \sim {10}^{-7\mathrm{}}-{10}^{-9\mathrm{}}$ sec. Though the theoretical prediction of a reduction in the effective local moment for a simple and somewhat unrealistic Hamiltonian was made by Kondo some eight years ago and the theory reformulated, refined and improved, only phenomenological models have been developed to reduce the Mössbauer-effect data. In this note we analyze data for dilute Fe concentrations in several cubic transition metals for evidence of the reduction of the moments localized about Fe impurities. These results and others from the literature will be summarized and compared.