A new ternary equiatomic compound, CeRhIn, has been synthesized which is found to crystallize in the hexagonal ${\mathrm{Fe}}_2$P structure. The unit-cell volume of this compound deviates from that expected on the basis of lanthanide contraction, indicating the nontrivalent state of the Ce ions in this compound. The magnetic susceptibility of CeRhIn shows a broad maximum at about 150 K. Such a maximum is a characteristic feature of the mixed-valent cerium compounds. The resistivity of CeRhIn due to magnetic scattering also shows a broad maximum at about 140 K. Thus from lattice volume, susceptibility, and resistivity measurements, it is concluded that cerium ions are in a mixed-valent state in CeRhIn.

• Received 4 November 1988

DOI:https://doi.org/10.1103/PhysRevB.39.4831