| Popis: |
RF SQUIDS with good characteristics were produced from Y1Ba2Cu3O7- delta ceramics. The best results were obtained from a high density ceramic, which is very stable, has larger grains and a small critical current density. Some often observed strange experimental characteristics were explained by multi-quantum flux transitions. The measured white flux noise at 77 K is about (6-7)*10-4 Phi 0 Hz-1/2 and therefore comparable with the noise of commercial 4.2 K RF SQUIDS. The 1/f-noise knee appears typically at 5 Hz, better than other similar high-Tc devices. |
