Influence of crossing angles of columnar defects on vortex glass transition in YBCO thin films

To investigate the influence of the crossing angles of columnar defects (CDs) on the in-field properties of the critical current density J(c) and the scaling parameter m derived from the isothermal current-voltage characteristics near the glass-liquid transition at B parallel to c-axis, YBCO thin films were irradiated using the 200 MeV Xe ions at two angles +/-theta(i) relative to the c-axis. For the thin films, the obvious effect of the crossing angle of CDs occurred on the vortex glass-liquid transition more than the J(c) properties. On the glass-liquid transition line, two inflection points induced by the c-axis correlated pinning were confirmed even for the samples of theta(i) = +/- 45 degrees. In the magnetic field dependence of m, the peak or kink appeared near B/B(phi) = 1/3 for the smaller crossing angles, whereas that was slightly visible for the samples of theta(i) = +/- 45 degrees. In addition, the values of m for the small crossing angle were larger than those for the parallel CD configuration, while those for the larger crossing angle became smaller. These results suggested that the morphologies of correlated pinning centers strongly affect the dynamics of flux lines even in the disordered system such as thin films. (C) 2011 Elsevier B.V. All rights reserved.