Flux flow effects in very long Josephson junctions

We report on measurements on very long, L similar or equal to 30 lambdaj, NbAlOxNb underdamped inline junctions, on which we observed displaced linear slope (DLS) generated by the application of an external magnetic field. We study the behaviour of the branches as a function of the applied magnetic field in terms of both current amplitude and voltage position. The DLS is seen to shift rigidly towards higher voltages when increasing the field, spanning a region roughly centred around the Josephson plasma frequency. We discuss the behaviour of linear branches in terms of one dimensional flux-flow along the extended side of the junction, comparing our data with the results of numerical modeling; from these calculations the non-resonant nature of DLS is very evident, in contrast to the resonant regime giving rise to Fiske steps (FS).