Nuclear Magnetic Resonance Studies of Magnetic Impurities in Metals

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Abstract
The application of nuclear magnetic resonance techniques to the study of magnetic impurity states in metals is reviewed. Two types of experimental information are considered. The first concerns resonance shifts and spin-lattice relaxation rates of isolated impurities, while the second concerns the effects of impurity-impurity interactions on these quantities. The theory of exchange-enhanced hyperfine interactions in metals is discussed for both elemental metals as well as impurities in metals. It is shown that the available low-temperature impurity data, which span a large range of 0°K susceptibilities, can be accounted for by treating the intra-atomic Coulomb and exchange interactions in the Hartree-Fock approximation. This even applies to two alloys, Au(V) and Mo(Co), which have previously been treated as Kondo systems. The present results therefore appear to remove the distinction between magnetic and nonmagnetic regimes of the magnetic impurity problem.