Vortex Dynamics in the High Temperature Superconductor YBa$_{2}$Cu$_{3}$O$_{7-\delta }$ with In-plane Columnar Defects

We investigated the vortex dynamics in a single crystal of YBa$_{2}$Cu$_{3}$O$_{7-\delta }$ before and after irradiation with high-energy heavy ions. Earlier studies have focused on the effects of irradiation-induced columnar defects parallel to the crystallographic c-axis of the crystal or at relatively large angles off the ab-plane. In our current study, we introduced columnar defects \textit{along the in-plane layered structure} of the crystal. A single crystal of YBa$_{2}$Cu$_{3}$O$_{7-\delta }$ was polished down to a narrow width of 27 $\mu $m allowing high energy heavy ions to penetrate the crystal along the ab-plane. The crystal was irradiated with 1.4 GeV $^{208}$Pb$^{56+}$ ions to a dose matching field of 1T. We present analysis of vortex dynamics under various current densities, magnetic field strengths and orientations. This work was supported by the US Department of Energy, under contract DE-AC02-06CH11357 and by National Science~Foundation under grant No. DMR-0072880.