Electron beam irradiation of Y1Ba2Cu3O72x grain boundary Josephson junctions

The properties of the Y1Ba2Cu3O72x biepitaxial Josephson junctions were reproducibly modified by a focused electron beam irradiation of the interface region. The junctions were fabricated by depositing Y1Ba2Cu3O72x thin film by cylindrical magnetron sputtering technique on the ~110! SrTiO3 substrate, partially covered by a pregrown MgO seed layer. The junction parameters can be adjusted controllably by applying an appropriate dose. Electron irradiation decreased the critical current of the junctions IC and increased the normal state resistance times area to values of the order of 1(m V cm). Some other effects, such as the disappearance of the excess current, were also observed. The original properties of the junctions could be partly restored by isothermal annealing. We also speculate that some aspects of the nature of the grain boundary barriers can be better understood from the study of the properties of irradiated junctions. © 1997 American Institute of Physics. @S0003-6951~97!03127-6#