Soliton excitations in Josephson tunnel junctions

P. S. Lomdahl, O. H. Sørensen, Peter Leth Christiansen

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    A detailed numerical study of a sine-Gordon model of the Josephson tunnel junction is compared with experimental measurements on junctions with different L / λJ ratios. The soliton picture is found to apply well on both relatively long (L / λJ=6) and intermediate (L / λJ=2) junctions. We find good agreement for the current-voltage characteristics, power output, and for the shape and height of the zero-field steps (ZFS). Two distinct modes of soliton oscillations are observed: (i) a bunched or congealed mode giving rise to the fundamental frequency f1 on all ZFS's and (ii) a "symmetric" mode which on the Nth ZFS yields the frequency Nf1 Coexistence of two adjacent frequencies is found on the third ZFS of the longer junction (L / λJ=6) in a narrow range of bias current as also found in the experiments. Small asymmetries in the experimental environment, a weak magnetic field, e.g., is introduced via the boundary conditions of our numerical model. This gives a junction response to variations in the applied bias current close to that observed experimentally.
    Original languageEnglish
    JournalPhysical Review B
    Issue number9
    Pages (from-to)5737-5748
    Publication statusPublished - 1982

    Bibliographical note

    Copyright (1982) by the American Physical Society.

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