Temperature dependence of the vortex motion along twin planes in YBa 2Cu 3O 7−δ

Abstract

Using a high resolution magneto-optical technique, flux motion along the twin planes of a high quality YBa 2Cu 3O 7− δ single crystal was systematically studied when an external magnetic field was applied along the c-axis of the crystal. Our results support the concept that whether or not the twin planes act as a barrier or a channel for vortex motion depends not only on the temperature, but also on the direction of vortex motion with respect to the twin plane. At low temperatures, the twin planes, regardless of their directions, act as easy-flow channels for vortices to preferentially penetrate, while at high temperatures, the twin planes that are not parallel to the direction of vortex motion act as barriers to vortex motion. Secondly, at low temperatures, we have also observed a twin barrier that must be overcome before the channelling effect starts. Finally, the results clearly show flux creep along the twin planes at a temperature of 25 K.