Inhaltszusammenfassung

In this article we report on thermally excited flux creep and the critical transport current density jc in high-quality epitaxial Bi2Sr2CaCu2O8 ? thin films. Both dissipative mechanisms are governed by the highly anisotropic behavior of this compound which was investigated by means of the angular dependence of the magnetoresistivity (??150). The activation energy U for thermally excited flux creep was evaluated with respect to temperature, magnetic field, and applied current density j. U(T,B,...In this article we report on thermally excited flux creep and the critical transport current density jc in high-quality epitaxial Bi2Sr2CaCu2O8 ? thin films. Both dissipative mechanisms are governed by the highly anisotropic behavior of this compound which was investigated by means of the angular dependence of the magnetoresistivity (??150). The activation energy U for thermally excited flux creep was evaluated with respect to temperature, magnetic field, and applied current density j. U(T,B,j) is essentially increasing linearly with falling temperature, power-law dependent on the field (U?B-? with ??0.5), and almost independent of current density for j?105 A/cm2. These experimental results are consistent with the concept of plastic flux creep. The critical current density exhibits high absolute values [jc(77 K, B=0)=4×105 A/cm2] and was measured for magnetic fields in the configuration B?c up to 10 T and also with respect to various ? angles between the c axis and field direction. The decrease of jc with increasing B was found to be significantly reduced in comparison to single crystals and prior results on thin films. A further enhancement in the jc(B,T) behavior could not be achieved by chemical doping through partial substitution of copper by zinc.» weiterlesen» einklappen

Autoren

Klassifikation

DFG Fachgebiet:
Physik der kondensierten Materie

DDC Sachgruppe:
Physik