Dynamics of semifluxons in Nb long Josephson 0-pi junctions.
We propose, implement, and test experimentally long Josephson 0-pi junctions fabricated using conventional Nb-AlOx-Nb technology. We show that by using a pair of current injectors one can create an arbitrary discontinuity of the Josephson phase and, in particular, a pi discontinuity, just as 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 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 the hopping of semifluxons.
Physikalisches Institut, Experimentalphysik II, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tuebingen, Germany. gold@uni-tuebingen.de
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Goldobin
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Sterck
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Gaber
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Koelle
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Kleiner