The crystallographic, magnetic and electronic properties of RM(2)X(2) (R=La, Ce, Pr; M=Cu, Ni; X=Sn, Sb)

The crystallographic structure, magnetic properties and X-ray photoemission spectra of PrNi2Sn2, PrCu2Sn2, PrNi2Sb2 and PrCu2Sb2 are investigated. Two phases occur for PrNi2Sn2 and PrNi2Sb, depending on preparation, the first being tetragonal, the other monoclinic. The compounds are antiferromagnets below T similar or equal to 5 K, in the magnetic field a phase transition of the spin-flip type is observed. The critical magnetic fields are small. The magnetic susceptibility suggests that Pr is nearly trivalent and the crystal field splittings are weak. We also report valence band and 3d core-level X-ray photoemission spectroscopy (XPS) data of LaM(2)X(2), CeM(2)X(2) and PrM(2)X(2), where M = Ni, Cu and X = Sn, Sb. The light rare-earth 3d spectra show in these compounds a satellite structure, which we discuss. We attempt an analysis of these core-level spectra using the Gunnarsson-Schonhammer model. A large hybridization of the f orbitals with a conduction band is characteristic for all the investigated compounds. The XPS valence bands are compared with self-consistent band structure calculations of the LMTO type, and are discussed.