High current driven vortex instability in YBa2Cu3O7−δ thin films — Analysis in terms of self organized criticality

Abstract

For high transport currents, a characteristic instability has been observed in YBa2Cu3O7−δ superconducting films with a voltage jump occurring at a well-defined current I*. The temperature and magnetic field dependence of the characteristic currents I* show scaling relations similar to what is known for the critical currents Ic suggesting an interpretation of the instability as a pinning-depinning transition. In the present work, the instability is analyzed in terms of a recent model based on self-organized criticality, which should be applicable close to such a transition. It turns out that the I – V characteristics for I ≤ I* can well be described within this model allowing to extract the ‘true’ depinning critical currents Ic(T,H), which in turn, are found to exhibit standard power laws for their field and temperature dependence. Combined with the observed linear relation I* = 0.94Ic, this immediately explains the experimentally obtained I*(T,H) behavior.