Electronic, transport, and magnetic properties of CaxCo4Sb12 partially filled skutterudites
Résumé
The physical properties of partially filled CaxCo4Sb12 (x = 0.03, 0.05, 0.10, and 0.20) skutterudites have been investigated at low temperature. Electrical, transport, and magnetic data completed by specific heat data are discussed in view of electronic structure Korringa-Kohn-Rostoker method with consistent potential approximation calculations. Unusual electron transport characteristics in CaxCo4Sb12—namely, a complex variation of resistivity curves whereas a rather systematic variation of thermopower with Ca content—seem to be governed by a remarkably large s-like density of states appearing at the conduction band. These features corroborate the large effective masses estimated from Hall and thermopower measurements. The evolution of the density of states near the Fermi level agrees with the sign and variation of the Seebeck coefficient slope alpha/T versus Ca content. The comparison between the values of the electronic specific heat of Ca0.20Co4Sb12 and Co4Sb12 apparently supports the finite density of states at EF in Ca0.20Co4Sb12. The analyses of the Pauli paramagnetic susceptibility and specific heat behaviors concerning the carrier effective mass are coherent both with the electron transport measurements and the electronic structure features.
Origine : Fichiers éditeurs autorisés sur une archive ouverte