OBSERVATION OF COHERENT MODES OF JOSEPHSON VORTICES IN BI2SR2CACU2OX

We report strong evidence for coherent modes of moving Josephson vorti ces in mesas patterned on the surface of Bi2Sr2CaCu2Ox single crystals . The vortex How current-voltage curves are characterized by a sharp u p-turn and the appearance of multiple branches as the current is rampe d up and down at a fixed magnetic field and temperature. These results are consistent with weakly damped motion of Josephson vortices in whi ch different coherent modes can occur in a close stack of Josephson co upled multilayers. (C) 1997 American Institute of Physics.