Axisymmetric Coherent Vortex States In AC Driven Josephson Junctions Arrays

摘要: We study the dynamic response of disordered Josephson junction arrays driven by dc and ac currents. The are modelled a set coupled non-linear overdamped oscillators external current. effect Johnson thermal noise is Langevin term in equations motion. disorder introduced randomly displacing bonds square lattice. find nucleation vortex pairs at defects produced After transient time these vortices unbind radiate other vortices. These radiated settle into parity-broken periodic axisymmetric coherent state characterized rows lying along tilted axis. This has properties that suggestive similar far from equilibrium states found hydrodynamic systems. ACVS produces steps current voltage characteristics typical giant Shapiro steps. Connections results to experiments done Nb-Au-Nb discussed.