Using YBa2Cu3O7-x (YBCO) thin films (0.5∼1.0 µm in thickness) with c axis orientation, we fabricated dc superconducting quantum interference devices (SQUIDs). YBCO films were deposited on MgO(100) single-crystal infstrates by MOCVD. These films exhibit zero resistance above 80 K and critical current density of 104 to 105 A/cm2 at 77 K. The SQUIDs with microbridge are fabricated by photolithography and chemical etching techniques. The maximum voltage modulation is about 80 µV for the YBCO dc SQUID with an inductance of 70 pH, and intrinsic energy sensitivity is 740 h (h: Planck’s constant) at 4.2 K. Furthermore, the SQUID was operated in flux-locked loop. The minimum flux noise in the flux-locked SQUID is 1.5×10-5φ0/√Hz in the white noise region at 4.2 K. The experiments suggest that the current-phase relationship of a micrometer-long YBCO bridge may be sinusoidal.
|Journal||Japanese journal of applied physics|
|Issue number||10 A|
|Publication status||Published - 1989 Oct|
- Thin film bridge
- Ybco dc SQUID
ASJC Scopus subject areas
- Physics and Astronomy(all)