SUBHARMONIC STRUCTURE OF SHAPIRO STEPS IN FRUSTRATED SUPERCONDUCTING ARRAYS

摘要: Two-dimensional superconducting arrays with combined direct and alternating applied currents are studied both analytically numerically. In particular, we investigate in detail current-voltage characteristics of a square array 1/2 flux quantum per plaquette triangular 1/4 plaquette. At zero temperature reduced equations motion obtained through the use translational symmetry present systems. The lead to series subharmonic steps addition standard integer fractional giant Shapiro steps, producing devil`s staircase structure. This structure reflects existence dynamically generated states originating from degenerate ground equilibrium. Widths as functions amplitudes display Bessel-function-type behavior. We also results extensive numerical simulations, which indeed reveal together their stability against small thermal fluctuations. Implications for topological invariance discussed.