Magnetic, thermal and electronic properties of Ce11Ni4In9 and CeNi9In2

Crystal structure, magnetic, thermal and electronic properties of Ce11Ni4In9 and CeNi9In2 compounds were investigated by means of X-ray diffraction, magnetic, calorimetric and X-ray photoelectron spectroscopy measurements. Ce11Ni4In9 crystallizes in the orthorhombic Nd11Pd4In9-type structure (space group Cmmm) while CeNi9In2 crystallizes in the YNi9In2-type structure (space group P4/mbm) (in which Ce atoms occupy only one Wyckoff position). Magnetic and specific heat measurements indicate that in Ce11Ni4In9 the Ce magnetic moment orders below 16.5 K, while in CeNi9In2 it does not carry a localized moment. Our data indicate that Ni atoms are likely non-magnetic in both compounds. The XPS spectra of the valence band and the core-level are reported. The contributions to the density of states at EF are dominated by the Ni3d states. The XPS Ce3d data indicate sizable hybridization of the Ce-4f electrons with conduction band for both compounds. The existence in CeNi9In2 of Ce3d94f0 configuration indicates a mixed-valence system. The core-level Ni2p3/2 spectra indicate incomplete Ni3d band filling in this compound.