SUPPRESSION OF IC AND FISKE RESONANCES IN SPECIALLY SHAPED JOSEPHSON-JUNCTIONS

In some applications of Josephson junctions it is necessary to suppres s the critical current and Fiske resonances with a relatively small ma gnetic field. The sidelobes of the Fraunhofer pattern can be suppresse d by taking an appropriate shape for the junction. A suppression of th e first sidelobe below 1% of the zero-field critical current is possib le as was shown experimentally. However, Fiske resonances are still pr esent. We investigated how an adaptation of the junction shape may sup press these resonances, still maintaining the suppression of the sidel obes of the Fraunhofer pattern. Measurements of the critical current a nd Fiske resonance heights as a function of the magnetic field for a j unction with a special shape and an adapted specially shaped junction were performed. For both types of junctions, the sidelobes of the I(c) (B) patterns are suppressed. No extra suppression of the I(F)(B) patte rns due to the adaptation of the shape is observed.