Flux flow in YBa2Cu3O7-delta grain-boundary Josephson junctions with a four-terminal configuration

We report on the observation in current-voltage characteristics of YBa2Cu3O 7-delta (YBCO) step-edge Josephson junctions of resistive branches generate d by a current injected close to the grain-boundary region through two symm etrical Au/YBCO contacts. The current amplitude and voltage tunability of t he branches is measured as a function of injected current and sample temper ature and the observed effects are explained in terms of flux-flow dynamics in long Josephson junctions. As the voltage of the branches can be tuned u p to 2.5 mV, the investigated phenomenon is also appealing for practical ap plications in the submillimeter-wave range of the electromagnetic spectrum. We estimate the available power and the linewidth of the electromagnetic r adiation associated with typical bias points. (C) 2000 American Institute o f Physics. [S0003-6951(00)03018-7].