Electronic structure and magnetic properties of RCuIn (R = La, Ce, Pr, Nd and Lu) compounds

Abstract

The electronic structure of the ternary RCuIn (R = La, Ce, Pr, Nd and Lu), compounds which crystallize in the hexagonal ZrNiAl-type structure, was studied by X-ray photoelectron spectroscopy measurements. The valence bands and XPS core-levels were investigated. The obtained results indicate that the valence bands are mainly determined by the Cu 3d band. The Pr 4f and Nd 4f states hybridize with the Cu 3d state. The analysis of R 3d spectra on the basis of the Gunnarsson–Schönhammer model gives the hybridization of the 4f orbitals with the conduction band equal 45 meV for CeCuIn, 181 meV for PrCuIn and 96 meV for NdCuIn. The appearance of the 3d 94f 0 component in CeCuIn is a clear evidence of the intermediate valence behavior of Ce. The 4f-occupation number is 0.95. Magnetic data indicate that RCuIn compounds with R = La and Lu are Pauli paramagnets, with R = Ce and Pr are Curie–Wiess paramagnets down to 2 K, while NdCuIn is an antiferromagnet below T N = 4.9 K.