A detailed numerical study on the directed motion of ac-driven vortices and antivortices in 2D Josephson junction arrays (JJA) with an asymmetric periodic pinning potential is reported. Dc-voltage rectification shows a strong dependence on vortex density as well as an inversion of the vortex flow direction with ac amplitude for a wide range of vortex density around f=1/2 (f=Ha2/Φ0), in good agreement with recent experiments by Shal\'om and Pastoriza [Phys. Rev. Lett. {\bf 94}, 177001 (2005)]. The study of vortex structures, spatial and temporal correlations, and vortex-antivortex pairs formation gives insight into a purely collective mechanism behind the current reversal effect.
@article{arxiv.cond-mat/0612390,
title = {Rocking ratchets in 2D Josephson networks: collective effects and current reversal},
author = {Verónica I. Marconi},
journal= {arXiv preprint arXiv:cond-mat/0612390},
year = {2007}
}
Comments
4 pages, 5 figures. Accepted for publication in Phys. Rev. Lett