Internal resonances in periodically modulated long Josephson junctions

Current-voltage (I-V) characteristics of long Josephson junctions with a periodic lattice of localized inhomogeneities are studied. The interaction between the moving fluxons and the inhomogeneities causes resonant steps in the IV-curve. Some of these steps are due to a synchronization to resonant Fiske modes in the sub-junctions formed between the inhomogeneities. The voltage positions of the resonant steps oscillate as function of the applied magnetic field with a period corresponding to the inclusion of one magnetic flux quantum, /spl Phi//sub 0/=h/2e, per sub-junction. A qualitative explanation that takes into account the interaction between the resonance in the sub-junction and the magnetic flux density waves excited in the whole junction is given.<>