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Magnetoresistance in HTSC far above Tc: fluctuations versus normal-state contributions

Authors/others:Lang, W.Heine, G.Liebich, W.Wang, X. L.Wang, X. Z.
Abstract:We discuss the temperature dependence of the anisotropic magnetoresistance in high temperature superconductors with a focus on the magnetoresistance at temperatures significantly above T/sub c/. Recent results on YBa/sub 2/Cu/sub 3/O/sub 7- delta / thin films and single crystals are analyzed and measurements of the in-plane and out-of-plane magnetoresistance in optimally doped Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8+x/ single crystals are reported. The in-plane magnetoresistance of both YBa/sub 2/Cu/sub 3/O/sub 7- delta / and Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8+x/ is positive for magnetic fields oriented perpendicular and parallel to the current. The out-of-plane magnetoresistance of Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8+x/ is negative from 94 to 180 K. The results are discussed considering the magnetic-field suppression of superconducting fluctuations including the Aslamazov-Larkin and Maki-Thompson terms, the normal-state magnetoresistance of quasiparticles, and the reduction of the quasiparticle density of states due to condensation into superconducting fluctuations. A crossover from fluctuation-induced in-plane magnetoresistance close to T/sub c/ to the quasiparticle effect was found around 1.25 T/sub c/. The out-of-plane magnetoresistance is dominated by the density-of-states contribution. All results indicate that superconducting fluctuations persist up to at least 2T/sub c/.
Number of pages:10
Date of publication:1997
Publication Series:Nato Science Partnership Subseries: 3, vol. 32,
Digital Object Identifier (DOI):http://dx.doi.org/10.1007/978-94-011-5536-6_6
Bibliographical note:Fluctuation-Phenomena-in-High-Temperature-Superconductors.-Proceedings-of-a-NATO-Advanced-Research-Workshop. 1997: 81-90 Netherlands Conference-Paper English
Publication Type:Chapter
Host publication's title:Fluctuation Phenomena in High Temperature Superconductors
Host publication's editors:Ausloos, MarcelVarlamov, Andrei A.
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