Inhaltszusammenfassung

The current-voltage characteristics of epitaxial Bi2Sr2Ca2Cu3O10 ? films in zero applied magnetic field were investigated in a temperature interval of about 20 K below the mean-field critical temperature Tc0=110.4 K. Despite the large anisotropy (??200), the data clearly indicate the occurrence of a finite critical-current density, resulting from the Josephson coupling between the (CuO2)3 layers. By analyzing the shape of the current-voltage characteristics in terms of quasi-two-dimensional v...The current-voltage characteristics of epitaxial Bi2Sr2Ca2Cu3O10 ? films in zero applied magnetic field were investigated in a temperature interval of about 20 K below the mean-field critical temperature Tc0=110.4 K. Despite the large anisotropy (??200), the data clearly indicate the occurrence of a finite critical-current density, resulting from the Josephson coupling between the (CuO2)3 layers. By analyzing the shape of the current-voltage characteristics in terms of quasi-two-dimensional vortex unbinding, it was found that this ??intrinsic?? critical-current density vanishes well below Tc0, just above the hypothetical Kosterlitz-Thouless transition temperature (TKT?94.8 K). This is in agreement with Monte Carlo simulations, suggesting a vortex-fluctuation-induced layer decoupling in the case of quasi-two-dimensional superconductors. However, close to the layer decoupling temperature, an excess dissipation beyond the quasi-two-dimensional vortex unbinding model appears. This excess dissipation was attributed to the excitation of three-dimensional vortex structures close to the resistive transition.» weiterlesen» einklappen

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Klassifikation

DFG Fachgebiet:
Physik der kondensierten Materie

DDC Sachgruppe:
Physik