Pinning effect on fluctuation conductivity in a superconducting untwinned YBa2Cu3O7-delta single crystal with columnar defects

Abstract

The effect of columnar defects on the critical dynamics of a superconducting untwinned YBa2Cu3O7−δ (YBCO) single crystal has been investigated. The columnar defects are produced by Sn ion irradiation of which dose corresponds to a matching field of 1 T. The in-plane longitudinal resistivity of the irradiated YBCO crystal has been measured as a function of magnetic field H and temperature T. The extracted fluctuation conductivities are enhanced by the strong pinnings and do not exhibit the same three-dimensional (3D) XY scaling behavior as for the unirradiated YBCO single crystal; particularly at the magnetic field values near the matching field of 1 T, the fluctuation conductivities show a clear deviation from the critical dynamics. At higher magnetic fields, however, the signature of the 3D-XY scaling appears.