Münster 1997 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 8: Transporteigenschaften und Flußverankerung in HTSL
TT 8.2: Vortrag
Dienstag, 18. März 1997, 10:30–10:45, F1
C-axis thermopower and magnetoresistance in Bi2Sr2CaCu2O8 single crystals — •G. Logvenov, O. Waldmann, R. Kleiner, and P. Müller — Physikalisches Institut III, Universität Erlangen-Nürnberg
We report on the temperature and magnetic field dependence of the c-axis thermopower and resistance in small high quality Bi2Sr2CaCu2O8 (BSCCO) single crystals. Below Tc, where the resistivity monotonically decreases, the temperature dependence of the thermopower is nonmonotonic. The well known relation between the mixed state thermopower, Sm(T,H), and resistivity, ρm(T,H), Sm(T,H)=Sn/ρn · ρm(T,H), is not satisfied anymore; here Sn, and ρn are the normal state thermopower and resistivity respectively. We show that in this regime there is a contribution from the superconducting transition of the CuO2 planes as well as a contribution from the intrinsic Josephson junctions that are formed between the CuO2 planes. As a function of a magnetic field, H⊥, applied perpendicular to the layers, the magnetoresistance exhibits pronounced hysteresis and a local maximum around H⊥∼ 0 which depends on the transport current and the parallel magnetic field component, H∥. We also attribute these features to the intrinsic Josephson effect along the c-axis.