Valence state of Ce and the magnetism in CeRh3B2

The compound Ce${\mathrm{Rh}}_3$ ${\mathrm{B}}_2$ orders magnetically with a high Curie temperature ($T_{\mathrm{Cj}}$) of 115 K but with a low moment of only ${0.4\mu }_B$. $L_{\mathrm{III}}$ absorption-edge measurements show a dominant absorption peak at the energy corresponding to trivalent cerium. Magnetic studies on the compounds $\mathrm{Ce}{\left({\mathrm{Rh}}_{1-x}{T}_x\right)}_3{\mathrm{B}}_2$ with $T=\mathrm{Ru}\mathrm{and}\mathrm{Os}$ and Os reveal that the magnetic state is very rapidly broken up with the replacement of Rh by Ru and Os. These results, along with the observation of a high $T_C$ in Ce${\mathrm{Rh}}_3$ ${\mathrm{B}}_2$, suggest that magnetism in this compound arises from a strong hybridization of nearly localized or slightly delocalized Ce $4f$ electrons with conduction electrons. The small moment may be due to a Kondo-type interaction coupled with crystal-field effects.