Low-temperature vortex dynamics in twinned superconductors.

The low-temperature dynamics of magnetic flux lines driven to move transverse to family of parallel twin planes maps onto the dynamics of carriers in [ital one[minus]dimensional] disordered semiconductors. As in flux arrays with columnar pins, there is a regime where the dynamics is dominated by superkink excitations that correspond to Mott variable-range hopping (VRH) of carriers. In one dimension, however, rare events, such as large regions void of twin planes, can impede VRH and dominate transport in samples that are sufficiently long in the direction of flux motion. In short samples rare regions can be responsible for mesoscopic effects.