Paramagnetic Susceptibilities of Metallic Samarium Compounds

Abstract

It is shown that the influence of conduction-electron polarization effects upon the susceptibilities of metals containing the tripositive samarium ion is very much greater than upon metals containing normal rare earths. A theory of the susceptibility of metallic samarium materials is developed which takes account of these polarization effects and of interionic Heisenberg exchange couplings, the admixture of the $J=\frac{7}{2}$ state into the $J=\frac{5}{2}$ ground state, which is assumed to be the only one to be thermally populated, but which, however, does not take account of crystal-field splittings. The susceptibility is found to be of the unexpectedly simple form $\ensuremath{\chi}(T)={\ensuremath{\chi}}_{0}+\frac{D}{(T\ensuremath{-}\ensuremath{\theta})}$, in which the only dependence on temperature $T$ is that explicitly shown. This expression is found to fit the published data for the susceptibility of dhcp samarium to an accuracy of 1% in the temperature region 110-230 \ifmmode^\circ\else\textdegree\fi{}K, and the parameters extracted from the fit are found to be in excellent agreement with those obtained for the other light rare-earth metals. An expression is also derived for the susceptibilities of metals containing normal rare earths, which takes account of both conduction-electron polarization and crystal field effects.