Influence of the columnar defect densities on the current–voltage characteristics in high-Tc superconductors

We investigated the influence of columnar defect densities on the critical exponents estimated from the critical scaling analysis of the current–voltage characteristics in high-Tc superconductors. It was found that the dynamic critical exponent z increased with increasing columnar defect densities, systematically. The peak of z was observed near the magnetic field B/BΦ=1/3. These results are explained by the depinning model considering the distribution of the pinning strength rather than the vortex-glass model.