Evidence of pseudogap formation in a new valence-fluctuating compound: CeRhSb

The compound CeRhSb, crystallizing in the orthohombic CeCu2-type structure, has been synthesized. Its unit-cell volume is anomalous in relation to that of isostructural RRhSb (R=rare earth) compounds. Its magnetic susceptibility is weakly temperature dependent and exhibits a broad maximum at about 113 K, characteristic of valence-fluctuating Ce compounds. The resistivity also shows a broad maximum at 113 K followed by a rapid rise below 21 K. The latter indicates a gap formation in the electronic density of states. The gap energy is estimated to be about 4 K. Thus CeRhSb appears to represent a valence-fluctuating cerium compound in which a pseudogap develops in the electronic density of states at low temperatures.