An ion-beam-assisted process for high-Tc Josephson junctions

This is the authors' abstract. We don't add key points for this paper.

We have developed a non-ion-etching ion-beam-assisted-deposition (IBAD) process for fabricating high critical-temperature (Tc) grain boundary Josephson junctions through a photoresist liftoff mask. The YBa2Cu3O7 (YBCO) junctions fabricated through this process exhibited the resistively-shunted-junction (RSJ)-like I–V characteristics. The well-defined Shapiro steps have been seen on the I–V curves under microwave radiation. The magnetic modulation of critical current of a 4 μm width YBCO junction tallied with the prior simulated Fraunhofer diffraction pattern of a Josephson junction with a spatially homogeneous critical current density. The maximum peak-to-peak modulation voltage across the dc superconducting quantum interference device (SQUID) fabricated by using these junctions reached up to 32 μV at 77 K. The magnetic modulation of the SQUID exhibited periodic behavior with the observed modulation period of 5.0×10−4 G.