Coexistence of magnetic order and valence fluctuations in the Kondo lattice system Ce2Rh3Sn5

We report on the electronic band structure, structural, magnetic, and thermal properties of Ce2Rh3Sn5. Ce LIII-edge XAS spectra give direct evidence for an intermediate valence behavior. Thermodynamic measurements reveal magnetic transitions at TN1≈2.9 K and TN2≈2.4 K. Electrical resistivity shows behavior typical for the Kondo lattices. The coexistence of magnetic order and valence fluctuations in a Kondo lattice system we attribute to a peculiar crystal structure in which Ce ions occupy two distinct lattice sites. Analysis of the structural features of Ce2Rh3Sn5, together with results of electronic band structure calculations and thermodynamic and spectroscopic data indicate that at low temperatures only Ce ions from the Ce1 sublattice adopt a stable trivalent electronic configuration and show local magnetic moments that give rise to the magnetic ordering. By contrast, our study suggests that Ce2 ions exhibit a nonmagnetic Kondo-singlet ground state. Furthermore, the valence of Ce2 ions estimated from the Ce LIII-edge XAS spectra varies between +3.18 at 6 K and +3.08 at room temperature. Thus our joined experimental and theoretical investigations classify Ce2Rh3Sn5 as a multivalent charge-ordered system

Onset of Itinerant Ferromagnetism in Cobalt-Nickel Heusler-Type Compounds

The magnetic properties of Co-Ni compounds with MnCu_{2}Al or MgAgAs-type structure (the Heusler phases) were studied. Paramagnetic, ferromagnetic moments, Curie's temperature increase with Co content. The ratio of ordered to paramagnetic moment varies with the Curie temperature following itinerant ferromagnetism models. A metal-insulator transition occurs in the TiCo_{x}Ni_{1-x}Sn series, which causes a more rapid drop of the Curie temperature than in TiCo_{x}Ni_{2-x}Sn solid solutions which remain metallic

Magnetic and Transport Properties of RNiSb Compounds (R = Gd, Tb, Dy, Yb, Lu)

The structural, magnetic, electrical and thermoelectric properties of heavy rare-earths ternary compounds RNiSb were investigated. Except Yb-based compound (and nonmagnetic Lu), all compounds are low temperature antiferromagnets. YbNi$\text{}_{0.9}$Sb reflects some mixed valence behaviour. Magnitude of the resistivity indicates that investigated compounds are semimetals or high doped semiconductors