Flux flow in different types of long-overlap Josephson junctions has been investigated by low-temperature scanning electron microscopy. The experimental results are compared with detailed numerical simulations. Describing the dynamics of the Josephson junction with the perturbed sine-Gordon equation, the flux-flow mode represents the case of high fluxon density in the junction. Due to the low damping in the investigated junctions (Nb/${\mathrm{AlO}}_{\mathit{x}}$/Nb and Nb/${\mathrm{NbO}}_{\mathit{x}}$/Pb based) a complicated interaction of the fluxon chain with reflected waves and cavity mode excitations occurred. The structure of these interactions was imaged with a spatial resolution of about 2 μm and investigated by the numerical simulations.

• Received 31 August 1994

DOI:https://doi.org/10.1103/PhysRevB.51.6542