2001/10/12 by Sylvie Hebert, Hebert, Sylvie, Christine Martin +9
Physics and Astronomy · #FOS: Physical sciences #Strongly Correlated Electrons (cond-mat.str-el) #cond-mat.str-el
paper · pdf · doi:10.48550/arxiv.cond-mat/0110270
8 pages, 13 figures, Proc. of the 6th European Workshop on Thermoelectrics (Freiburg 2001)
arxiv created 2001/10/12 · arxiv updated 2009/11/30
Two different kinds of metal transition oxides have been studied for their large thermopower values. The first one corresponds to the Tl-based misfit cobaltite which is a hole-doped metal. We demonstrate that the partial Bi-substitution for Tl in this phase induces an increase of the room temperature (RT) thermopower (TEP) value. Same result is obtained with the new Pb1/3SrCoO3+delta misfit corresponding to the Tl complete replacement by lead. Simultaneously, the T dependence of their resistivity exhibits a re-entrance below 70-90K where a large negative magnetoresistance is observed. Magnetic measurements reveal a strong interplay between spins and charges for this class of materials. Electron-doped (n-type) perovskite manganites are a second class of potential candidates for applications. In particular, the Ru4+/5+ substitution for Mn in the CaMnO3 semi-conductor induces a drastic drop of the resistivity values. Metals with large RT TEP values and not too large thermal conductivities are generated. A comparison with best known materials, Bi2Te3 and NaCo2O4 is made.