Electronic and transport properties of RAgSn (R=Ce, Pr, Nd, Dy) compounds

The electronic structure of the ternary RAgSn (R=Ce,Pr,Nd,Dy) compounds whi ch crystallize in the hexagonal LiGaGe-type structure was studied by X-ray photoemission spectroscopy. Core-levels and valence bands were investigated . The X-ray photoemission spectroscopy valence bands ale compared with the ones calculated using the spin-polarized tight-binding linear muffin-tin or bital method. The obtained results indicate that the valence bands are main ly determined by the Ag 4d band. The spin-orbit splitting values Delta (SO) determined from the XPS spectra of 3d(5/2) and 3d(3/2) are equal to 18.8 e V for R = Ce, 20.2 eV for R = Pr and 22.6 eV for R = Nd. The analysis of th ese spectra on the basis of the Gunnarsson-Schonhammer model gives a hybrid ization of f orbitals with the conduction band. The calculation of the tota l energy for two models of the crystal structure: an ordered of the LiGaGe- type and a disordered one of the CaIn2-type indicate that in these compound s the LiGaGe-type structure is stable. Additionally, the temperature depend ences of the electrical resistivity of CeAgSn and DyAgSn are investigated. At high temperatures the resistivity is not a linear function of temperatur e which indicates an electron-phonon interaction in the presence of a small s-d scattering, whereas at low temperatures anomalies connected with the m agnetic phase transitions are observed.