Physical properties of the skutterudites (Ce,La)Fe4-xNixSb12

R. Viennois1,2,3, L. Girard2, D. Ravot2, F. Terki1, S. Charar1, J. C. Tedenac2, S. Paschen3,

A. Bentien3, F. Steglich3.

1Groupe d’Etude des semiconducteurs, Université Montpellier II, Place Eugène Bataillon, 34095 Montpellier, Franc

2Laboratoire de Physicochimie de la Matiere Condensée, Université Montpellier II, Place Eugène Bataillon, 34095 Montpellier, France

3Max-Planck-Institut für Chemische Physik fester Stoffe, Nöthnitzer Str. 40, 01187 Dresden, Deutschland

Up to now, the fundamental physical properties of CeFe4Sb12 are not well understood. For improving this knowledge, we have studied the physical properties of (Ce,La)Fe4-xNixSb12 by magnetic, transport and thermodynamic experiments, the substitution of La for Ce allowing us to separate the itinerant and localized magnetism. We find heavy fermion and non-Fermi liquid behaviour in CeFe4Sb12 with a high Kondo temperature. We show that the crystal electric field and the contribution of the iron should be considered. If this last contribution is stronger in LaFe4Sb12 at low temperatures, it should be very similar for both compounds at room temperature as evidenced by the thermopower experiments. Therefore, the high density of state due to a large transition metal contribution in the band structure of skutterudite is believed to be the origin of the high thermopower in (Ce,La)Fe4-xNixSb12. In the second part of this work, we study the thermoelectric properties of (Ce,La)Fe4-xNixSb12 at room temperature and notably CeyFe4-xNixSb12 with y = 4/3 – 2x/3 below 300 K. Indeed, as already show previously, these compounds are heavily doped semiconductors and therefore have the best thermoelectric properties. We find the highest power factor S2s for y @ 0,5-0,6.