Rf-driven Josephson junctions: Tails on the shapiro steps of the I-V curves

rf-driven Josephson junctions have been experimentally studied in a wide parameter range corresponding to the low-frequency boundary of the chaotic regime, where the I-V curves display characteristic large negative-going tails on top of the Shapiro steps. The tail, in units of the Shapiro step spacing, has been found to increase with decreasing damping of the junction, in agreement with theoretical predictions using the resistively-shunted-junction model. © 1988 The American Physical Society.