Anisotropic vortex dynamics and phase diagram of YBa₂Cu₃O₇ single crystals with canted columnar defects

Abstract

The anisotropic vortex dynamics and phase diagram are determined for a YBa2Cu3O7 single crystal with columnar defects oriented at ±7.5° relative to the crystalline c-axis. A second-order splayed-glass to vortex-liquid transition is manifested for magnetic fields nearly parallel to the columns via the critical scaling of vortex AC and DC transport properties. In contrast, for magnetic fields aligned close to the ab-plane, an XY-like vortex-glass transition prevails. For magnetic fields at intermediate angles, there is no evidence of any vortex phase transition, and the vortex dynamics is described in terms of the thermally activated flux flow model.