We propose, implement and test experimentally long Josephson 0-pi junctions fabricated using conventional Nb-AlOx-Nb technology. We show that using a pair of current injectors, one can create an arbitrary discontinuity of the Josephson phase and in particular a pi-discontinuity, just like in d-wave/s-wave or in d-wave/d-wave junctions, and study fractional Josephson vortices which spontaneously appear. Moreover, using such junctions, we can investigate the \emph{dynamics} of the fractional vortices -- a domain which is not yet available for natural 0-pi-junctions due to their inherently high damping. We observe half-integer zero-field steps which appear on the current-voltage characteristics due to hopping of semifluxons.
@article{arxiv.cond-mat/0311610,
title = {Dynamics of semifluxons in Nb long Josephson 0-pi junctions},
author = {E. Goldobin and A. Sterck and T. Gaber and D. Koelle and R. Kleiner},
journal= {arXiv preprint arXiv:cond-mat/0311610},
year = {2007}
}
Comments
Fractional vortices in conventional superconductors ;-)