Generation of subharmonic shapiro steps in ladder arrays of overdamped superconducting junctions

Summary Subharmonic Shapiro Steps (SSS) are usually observed in 2D arrays of superconducting junctions when their dynamical states are perturbed by factors like disorder, frustration, current inhomogeneities and so on. In order to clarify the conditions under which SSS can be generated we decided to investigate arrays of very simple shape like the ladder ones. In particular we have studied the influence of the frustration (i.e. of an external magnetic field) on the time evolution of the vortex configuration and the commensurability of the latter with the geometry and the dimension of the array. Ladders, parallel or perpendicular to the bias current, turn out to be systems where the properties of the square arrays can be suitably tested. Paper presented at the ?VII Congresso SATT?, Torino, 4–7 October 1994.