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TT: Tiefe Temperaturen
TT 19: Supraleitung: Elektronenstruktur, Phononen, Tunneln, Ordnungsparameter II
TT 19.5: Vortrag
Donnerstag, 27. März 2003, 15:30–15:45, HSZ301
Magnetic-field induced finite-size effect in the high-temperature superconductor YBa2Cu3O7-d: an analogy to rotating 4He — •R. Lortz1,2, C. Meingast1, A.I. Rykov3, T. Masui3, and S. Tajima3 — 1Forschungszentrum Karlsruhe, Institut für Festkörperphysik, 76021 Karlsruhe, Germany — 2Fakultät für Physik, Universität Karlsruhe, 76131 Karlsruhe, Germany — 3ISTEC, 10-13 Shinonome I-Chome, Koto-ku, Tokyo 135, Japan
There is presently a great deal of interest in the effect of high magnetic fields on superconductivity, the pseudogap and on the AF-magnetic fluctuations in high-Tc superconductors. We have studied the response of the superconducting transition and the associated superconducting fluctuations in untwinned YBa2Cu3Ox single crystals to magnetic fields up to 10 T using high-resolution dilatometry, which was previously shown to be extremely useful in characterizing the zero-field transition. We show that the broadening of the superconducting transition in a magnetic field is a consequence of a finite-size scaling effect due the additional vortex-vortex length scale, which prevents the divergence of the coherence length at Tc. The behavior is analogous to that of the superfluid transition in rotating superfluid 4He [1]. Apart from this broadening, practically no field effect is observed on superconductivity and on superconducting fluctuations, which we observe up to about 30 K above Tc. [1] R. Haussmann, PRB 60, S. 12373 (1999).