Münster 1999 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 8: Josephson-Kontakte
TT 8.4: Vortrag
Dienstag, 23. März 1999, 11:15–11:30, F2
Whispering fluxons in annular Josephson junctions — •A. Wallraff1, A. Yulin2, V.V. Kurin2, A. Franz1, and A.V. Ustinov1 — 1Physikalisches Institut III, Universität Erlangen-Nürnberg, D-91058 Erlangen — 2Institute for Physics of Microstructure, Nizhny Novgorod, Russia
The interaction of Josephson vortices with plasma waves is investigated experimentally and numerically in wide annular Josephson junctions. Recently, it has been shown analytically that the vortex may come into resonance with linear electromagnetic modes of the annular Josephson junction [1] exciting waves of the whispering gallery type [2]. The Josephson vortex, being a topological soliton and moving as a quasiparticle, does exceed the velocity of linear waves v in the region of the junction in which ω r ≥ v, where r is the radius, depending on the angular velocity ω of the vortex. Therefore, the vortex does generate radiation of the Cherenkov type in the junction, similar to that observed recently in stacked junctions [3,4].
Experimentally, we have observed a very clear fine structure on single- and multiple-fluxon resonances of the current-voltage characteristics. The structure of the resonances strongly depends on the junction width, damping and number of fluxons trapped. We perform numerical simulations using the 2D sine-Gordon model with the experimental junction parameters and find a fine structure similar to that in experiment. Good agreement between analysis and numerical calculations is also found.
[1] V.V. Kurin et al., Phys. Rev. Lett. 80, 3372 (1998)
[2] Lord Rayleigh, Phil. Mag. 27, 100 (1914)
[3] E. Goldobin et al., Phys. Rev. B 57, 130 (1998)
[4] G. Hechtfischer et al., Phys. Rev. Lett. 79, 1365 (1997)