Dresden 2006 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 25: Correlated Electrons - Poster Session
TT 25.24: Poster
Mittwoch, 29. März 2006, 14:30–18:30, P1
Pressure studies on the polymeric compound methyltrioxorhenium (poly-MTO) (CH3)0.9ReO3 — •Valdeci Mariano de Souza1, Michael Lang1, Robert Miller2, Christian Helbig2, Ernst-Wilhelm Scheidt2, and Wolfgang Scherer2 — 1Physikalisches Institut, J.W. Goethe-Univeristät, Frankfurt am Main, Germany — 2Chemische Physik und Materialwissenschaften, Universität Augsburg, Germany
Transport measurements on the polymeric compound methyltrioxorhenium (poly-MTO) (CH3)0.9ReO3 have been performed in the temperature range 2-300 K and under 4He-gas pressure up to 10 kbar. The structural motive and transport properties of poly-MTO are reminiscent of those of classical perowskites in two dimensions. The metallic conductivity has been attributed to the presence of demethylated Re atoms giving rise to excess electrons which delocalize within the Re-5d bands. Upon cooling, the system remains metallic down to about 30 K, below which the resistivity starts to increase. In this non-metallic low-temperature range, the resistivity follows a log(1/T) dependence over one decade in temperature. Attempts to increase the electrical conductivity by intercalation with the organic donor molecule tetrathiafulvalene (TTF) showed that with increasing amount of TTF donors, the system becomes less conducting in the metallic high-temperature range and the low-T resistivity upturn is strongly reinforced. In contrast, the application of hydrostatic pressure results in a reduction of the resistivity over the whole T-range investigated, while the metal-to-insulator crossover around 30 K remains unaffected.