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

We investigated the influence of the crossing angles of columnar defects (CDs) on the vortex glass-liquid transition. On the glass-liquid transition line, two inflection were confirmed even for the large crossing angle of CDs. A peak or kink of the critical scaling parameter appeared near B/Bf = 1/3 for the smaller crossing angles. The values of the scaling parameters seemed to be sensitive to the flux line dynamics peculiar to the crossed CD configurations. To investigate the influence of the crossing angles of columnar defects (CDs) on the in-field properties of the critical current density Jc and the scaling parameter m derived from the isothermal current-voltage characteristics near the glass-liquid transition at B||c-axis, YBCO thin films were irradiated using the 200 MeV Xe ions at two angles ±θi 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 Jc properties. On the glass-liquid transition line, two inflection points induced by the c-axis correlated pinning were confirmed even for the samples of θi = ±45o. In the magnetic field dependence of m, the peak or kink appeared near B/Bφ = 1/3 for the smaller crossing angles, whereas that was slightly visible for the samples of θi = ±45o. 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.