Pulse I-V characteristics measurement to study dissipation mechanism in epitaxial YBaCuO thin films at high current densities

A simple pulse method of measuring current-voltage characteristics (I-V) at high current densities is described. We report I-Vs on epitaxial YBa₂Cu₃O_x thin films at high current densities in the presence of a magnetic field parallel to the c-axis. The results show that the Bardeen-Stephen flux flow model does not account for dissipation at high current densities in YBa₂Cu₃O_x thin films. In the presence of a magnetic field, we find qualitative agreement with a simple theoretical model based on dissipation caused by 2D vortices excited from the flux lines. In the absence of a magnetic field, a power law behavior arises due to current-induced depairing of thermally excited 2D vortices.