Absence of anomalously large conduction-electron polarization in superconducting rare-earth ternary compounds

An analysis of the paramagnetic susceptibility of Sm${\mathrm{Rh}}_4$ ${\mathrm{B}}_4$ indicates that conduction-electron polarization effects are relatively small in the $R{\mathrm{Rh}}_4{\mathrm{B}}_4$ compounds, where $R$ is a rare earth. The coexistence of superconductivity and magnetism is therefore allowed by the smallness of the exchange interaction between the rare earth and the conduction electrons. An expression for the paramagnetic susceptibility of metallic samarium compounds is successful in explaining recent measurements on polycrystalline rhombohedral samarium metal.