BEHAVIOR OF DOUBLE JUNCTION SQUID OF Y-Ba-Cu-O BULK SUPERCONDUCTOR

Abstract

A dc SQUID like geometry with a ring and a pair of constrictions is carved out of bulk Y-Ba-Cu-O superconductor. The I—V curves exhibit hysteresis arising due to trapping of the self fields. The V—Φ curves show multiple flux periodicities with unequal amplitudes. There is twenty fold rise in the amplitude of voltage modulation in cooling from 77 to 4.2 K. The complications of presence of series and parallel arrays of granular junctions are attributed respectively to large and small periodicities observed in V—Φ curves. The modulation structure gets more resolved at 4.2 K due to reduction in thermal noise effects.

Josephson effects and dc SQUID behaviour in break junction of Y-Ba-Cu-O at 77 K

“…Josephson effect and DC SQUID behaviour have been observed in high Tc superconductors by various groups. DC SQUID based on bulk (Kataria et al 1989), thick (Lin et al 1989) and thin films (Koch et al 1987(Koch et al , 1989Nakane et al 1987;Hauser et al 1988) have been made using intergranular weak links in small constriction of the sample. RF SQUID behaviour have been demonstrated in bulk sample of Y-Ba-Cu-O at 77K (CoMough et al 1987;Pegrum et al 1988;Tichy et al 1988).…”