Inhaltszusammenfassung

We report measurements on voltage instability at high flux-flow velocities in Bi2Sr2CaCu2O8 ? superconducting films. Current-voltage (I-V) characteristics have been measured as a function of temperature, magnetic field, and angle between the field and the c axis of the sample. Voltage jumps were observed in I-V characteristics taken in all magnetic-field directions and in extended temperature and field ranges. An analysis of the experimental data, based on a theory for viscous flux-flow insta...We report measurements on voltage instability at high flux-flow velocities in Bi2Sr2CaCu2O8 ? superconducting films. Current-voltage (I-V) characteristics have been measured as a function of temperature, magnetic field, and angle between the field and the c axis of the sample. Voltage jumps were observed in I-V characteristics taken in all magnetic-field directions and in extended temperature and field ranges. An analysis of the experimental data, based on a theory for viscous flux-flow instability with a finite heat-removal rate from the sample, yielded the inelastic scattering rate and the diffusion length of quasiparticles. Reasonable values of the heat-transfer coefficient from film to bath have been obtained. This theory can also successfully explain the observed scaling behavior I*(T,H)=I*(H)(1-T/Tco)3/2 with I*(H)?1/(1 H/H0)?, where Tco, H0, and ? are fitting parameters, determined by the temperature and magnetic-field dependence of the critical current I* at which the voltage jumps occur. A two-dimensional scaling for the angular dependence of the critical current I* and the critical voltage V* associated with the voltage jump has been found and interpreted with a model based on the two-dimensional behavior of this system. » weiterlesen» einklappen

Autoren

Klassifikation

DFG Fachgebiet:
Physik der kondensierten Materie

DDC Sachgruppe:
Physik