Current-voltage characterization of the vortex motion in YBa2Cu3O7-delta microbridges and the implications on the development of superconducting flux flow transistors

In order to develop superconducting thin films or multilayer structures suitable for Abrikosov vortex flux how transistors, we propose a model to describe the current-voltage characteristics measured on microbridges operating in the flux creep regime and we show how the effective superconducting thickness of the samples, as well as the pinning potential range, the maximum velocity, the pinning energy, and the depinning current of the vortices can be determined. This model is applied to microbridges with structures containing one or several YBa2Cu3O7-delta layers which were deposited either on LaAlO3 or on SrTiO3 substrates. The results demonstrate that most YBa2Cu3O7-delta microbridges exhibit very similar properties and are not suitable for flux flow devices. However, bilayer structures comprised of a YBa2Cu3O7-delta film and a conductive capping layer display interesting properties. (C) 1997 American Institute of Physics.