Barrier properties inYBa2Cu3O7−xgrain-boundary Josephson junctions using electron-beam irradiation

Electron-beam irradiation has been used to induce controllable variations in the properties of YBa2Cu3O72x biepitaxial grain-boundary Josephson junctions. A correlation between the transport properties and the microstructure was obtained by determining the ratio of a barrier thickness to the dielectric constant of the junctions with different barriers. These results give evidence of the role of the oxygen content and the dielectric constant of the interface region in transport phenomena. The experiment also demonstrates frequency tunability in a resonant soliton oscillator. @S0163-1829~98!51322-2#