Broken symmetry of row switching in 2D Josephson junction arrays

We present an experimental and theoretical study of row switching in two-di mensional Josephson junction arrays. We have observed novel dynamic states with peculiar percolative patterns of the voltage drop inside the arrays. T hese states were directly visualized using laser scanning microscopy and ma nifested by fine blanching in the current-voltage characteristics of the ar rays. Numerical simulations show that such percolative patterns have an int rinsic origin and occur independently of positional disorder. We argue that the appearance of these dynamic states is due to the presence of various m etastable superconducting states in arrays.