Impurity Diamagnetism in Metals

The results of a broad experimental survey of impurity magnetism in liquid monovalent metal solvents is reported. As the impurity valence Z is increased, a giant impurity diamagnetism {~} - 150 cm³/mole emerges in alkali-metal solvents for Z {~} 5. The diamagnetism is explained by the concept of impurity ionicity developed in this paper, and the impurity structure is analyzed in detail using the present results and earlier spin-flip-scattering results of Slichter and his co-workers. There is quantitative agreement between the theory of fully ionic impurities and the experimental susceptibilities for higher-valence impurities. The broad scheme of impurity structure in monovalent metals is also clearly revealed. The susceptibility of Sn is studied as a function of host-electron density, and the transition from band to resonant $5p$ orbitals is identified. A solubility dip occurs, but the data are not precise enough to determine whether the transition has a one-electron or configurational character. It is further reported that the large diamagnetism of positive-valence solutes in Ag, previously studied by Henry and Rogers, disappears at the melting transition. No detailed analysis of this striking effect has been attempted, but the anomalous impurity diamagnetism in the solid is clearly associated with orbits involving the [111] necks on the Fermi surface.