Anisotropic Vortex Motion Through Splayed Columnar Defects
Abstract
We report the results of the experiment designed to probe the anisotropy of vortex motion through splayed columnar pins in the c-axis oriented epitaxial YBCO films with two cris-crossing families of tilted columnar defects installed by irradiation with 1 GeV Au ions. The films were patterned in a geometry allowing control of the relative orientation between the external current and the splay planes in the same sample. Our results indicate that vortex motion is easier across the plane of the splay (across-fan) than in the splay plane (in-fan). This anisotropy translates onto an H-T phase diagram with two distinct lines -- the in-plane linear resistivity for the across-fan motion vanishes at lower temperatures than that for the in-fan motion. For our thin films the entanglement is not a controlling factor. We argue that the observed anisotropy is due to the in-plane tilt. We confirm this in films with only a single tilted family of columnar defects. The results are compared with data on thicker samples with splayed defects, where the entanglement plays a role.
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 1997
- Bibcode:
- 1997APS..MAR..J907K