Modification of the properties of YBaCuO biepitaxial Josephson junctions through electron beam irradiation

The properties of YBa2Cu3O7-x grain boundary Josephson junctions have been reproducibly modified by a focused electron beam irradiation. The original junctions were fabricated by using the biepitaxial technique on (110) SrTiO3, substrates. The technique utilizes the property of YBa2Cu3O7-x film to grow (103)-oriented on the bare substrate and (001)-oriented on the part of the substrate with the MgO seed layer, providing Josephson junctions of good quality and excellent reproducibility. The junction parameters can be adjusted controllably by applying an appropriate irradiation dose. Electron irradiation reduced the critical current of the junctions I-C and increased the normal state specific resistivity. The disappearance of the excess current and the shift of the voltage position of the Fiske steps were also observed. Isothermal annealing partly restores the original junction properties. We also speculate that some aspects of the nature of the grain boundary barriers can be better understood from the study of the transport properties of irradiated junctions.