Regensburg 1998 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 9: Vortex-Dynamik

TT 9.1: Hauptvortrag

Dienstag, 24. März 1998, 10:00–10:30, H 8

Field Induced Crossover of Criticalities of Vortex Dynamics in Tl₂Ba₂CaCu₂O₈ Thin Films — •Hai-hu Wen, P. Ziemann, and H.A. Radovan — Abteilung Festk"orperphysik, Universit"at Ulm, 89069 Ulm

By analyzing I-V characteristics (E-j curves) experimentally determined on Tl₂Ba₂CaCu₂O₈ thin films in magnetic fields B_e varying from 0 T to 5 T, we find that the transition of the linear resistivity ρ_lin = [E/j]_{j → 0}, signaling superconductivity, exhibits different criticalities for different magnetic fields. We will report a general behavior of criticalities of flux dynamics in highly anisotropic superconductors: starting with a Kosterlitz- Thouless transition at T_KT for B_e = 0 T, one induces a crossover to a quasi-2D or 3D vortex-glass transition at a finite T_g for magnetic fields below a few kOe, and finally a ’true’ 2D vortex-glass with T_g = 0 K for higher fields.