Electronic structure and magnetic properties of the compound CeCuIn Original Research Article

Magnetization, magnetic susceptibility, electrical resistivity, thermoelectric power and X-ray photoemission measurements were performed on a polycrystalline sample of CeCuIn. This compound crystallizes in a hexagonal structure of the ZrNiAl type. The magnetic data indicate that CeCuIn remains paramagnetic down to 1.9 K with a paramagnetic Curie temperature of −13 K and an effective magnetic moment equal to 2.5 μB. The electrical resistivity has metallic character, yet in the entire temperature range studied here, it is a strongly nonlinear function of temperature. The temperature dependence of the thermoelectric power is dominated by a small positive maximum near 76 K and a deep negative minimum at about 16 K. Above 150 K the thermopower exhibits a Mottʹs type behavior. The positive sign of the Seebeck coefficient in this temperature region indicates that the holes are dominant charge and heat carriers. The structure of Ce 3d5/2 and Ce 3d3/2 XPS spectra has been interpreted in terms of the Gunnarsson–Schönhammer theory. Three final-state contributions f0, f1 and f2 are clearly observed, which exhibit a spin–orbit splitting ΔSO≈18.7 eV. The appearance of the 3d9f0 component is a clear evidence of the intermediate valence behavior of Ce. From the intensity ratio I(f0)/[I(f0)+I(f1)+I(f2)] the 4f-occupation number is estimated to be 0.95. In turn, the ratio I(f2)/[I(f1)+I(f2)]=0.08 yields a measure of the hybridization energy that is equal to 45 meV.