Magnetic and electronic properties of RCoxGe2 (R = Pr, Nd) compounds

Magnetization, magnetic susceptibility, neutron diffraction and X-ray photoemission spectroscopy measurements were performed on polycrystalline samples: PrCo0.85Ge2 and NdCo0.82Ge2, crystallizing in an orthorhombic structure of the CeNiSi2-type. The magnetometric data indicate that both compounds are antiferromagnetic at low temperatures, PrCo0.85Ge2 below 5 K and NdCo0.82Ge2 below 2.1 K. The neutron diffraction data indicate an antiferromagnetic structure in PrCo0.85Ge2 at 1.5 K and give no evidence of any magnetic ordering in NdCo0.82Ge2. The X-ray photoemission data indicate that the valence bands are formed predominantly by R 4f5d6s and Co 3d bands. The spin-orbit splitting values determined from the Pr and Nd, 3d5/2 and 3d3/2 XPS spectra are equal to 20.9 eV for the Pr compound and 23.0 eV for the Nd compound. The analysis of these spectra performed on the basis of the Gunnarsson–Schönhammer model revealed a small hybridization between 4f-electrons of the rare earths with the conduction band which implies rather good stability of the f shell in these compounds.