Münster 1999 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 15: Postersitzung II: Elektronische Eigenschaften (1-12), Josephson-Kontakte (13-27), Heavy Fermions (28-40), Theorie HTSL (41-48), M-I-Überg
änge, Korrelierte Systeme (49-79)
TT 15.14: Poster
Mittwoch, 24. März 1999, 14:30–18:00, Foy
Fluxon radiation in multilayered Josephson junctions — •J. Zitzmann1, A. V. Ustinov1, N. Thyssen2, M. Levichev2, and S. Sakai3 — 1Physikalisches Institut III, Universität Erlangen-Nürnberg, D-91058 Erlangen — 2Institut für Schicht- und Ionen-Technik, Forschungszentrum Jülich, D-52425 Jülich — 3Electrotechnical Laboratory, 1-1-4 Umezono, Tsukuba-shi, Ibaraki 305, Japan
Experiments with single-fluxon states in stacked 5-junction and 10-junction Josephson rings are presented. We find that the current-voltage characteristic (CVC) of a fluxon moving in a stack is distinctly different from the conventional case of a fluxon in a single-barrier Josephson junction. The high-velocity part of the CVC displays a curvature change (non-monotonic behavior of its derivative) which is consistent with numerical simulations using the inductive coupling model. Numerical results indicate that this new feature is due to the Cherenkov radiation induced by a moving fluxon. The results presented extend the earlier study of 2-junction stacks [1] towards a larger (5 and 10) number of layers. As expected, we also observe resonances due to the interaction of the Cherenkov wave with a moving fluxon in the low damping regime.
We will also present our latest results of the experimental search for the broad band radiation in multi-junction low-Tc stacks in the flux-flow regime. This study is motivated by experimental findings of non-Josephson emission in high-Tc intrinsic junctions [2]. It is expected that in stacks with a large number of layers simultaneous Cherenkov emission occurs at many close frequencies. Mixing between these frequencies should lead to broad band emission searched for in our experiments.
[1] E. Goldobin et al., Phys. Rev. B 57, 130 (1998).
[2] G. Hechtfischer et al., Phys. Rev. Lett. 79, 1365 (1997).