Highly reliable dc SQUIDs in temperature with laser-MBE YBa2Cu3OX thin films

Highly reliable dc superconducting quantum interference devices (SQUIDs) in temperature with step edge junctions (SEJs) were fabricated with laser molecular beam epitaxy (L-MBE) YBa2Cu3OX thin films. The reflection high-energy electron diffraction oscillation cycles proved that the superconducting films were epitaxially grown on the atomic scale. In the dc SQUID temperature transition curves, the tail structures appear at a temperature close to the transition point. The critical current dependent temperature, IC∼(1−T/TC)2, shows that the L-MBE SEJ behaves like an SNS type junction. The white noise level, 2.0×10−5Φ0/Hz at 200 Hz, triangular wave signal, critical current and other characteristics exhibit no change after 42 temperature cycles and 108 days of storage.