Magnetic, electronic and transport properties of RAg2Ge2 (R=Pr, Nd) compounds

Magnetization, magnetic susceptibility, electrical resistivity, thermoelectric power, neutron diffraction and X-Ray photoemission spectroscopy measurements were performed on polycrystalline samples of PrAg2Ge2 and NdAg2Ge2, both crystallizing with a tetragonal structure of the ThCr2Si2-type. The data indicate that both compounds order magnetically at low temperatures, PrAg2Ge2 at 12 K and NdAg2Ge2 at 2 K. Neutron diffraction data for the latter indicate antiferromagnetic collinear structure described by the propagation vector k=(½, 0, ½) at 1.5 K. Both compounds exhibit metallic-like electrical behavior. The X-Ray photoemission data indicate that the valence bands are formed mainly by the Ag 4d bands. The spin-orbit splitting values determined from the XPS spectra of Pr and Nd, 3d5/2 and 3d3/2, equal 20.5 eV for the Pr compound and 22.7 eV for the Nd compound. The analysis of these spectra performed on the basis of the Gunnarsson-Schönhammer model indicates a weak hybridization of the 4f electrons with the conduction band.