Properties of Grooved Dayem Bridge Based YBa2Cu3O7−δ Superconducting Quantum Interference Devices and Magnetometers

The transport properties of a YBa2Cu3-delta superconducting quantum interference device (SQUID) based on grooved Dayem bridge weak links are studied as a function of temperature: at high temperatures (60 = 89 K), the weak links show properties similar to superconductor-normal conductor-superconductor junctions, while at temperatures below 60K, the weak links behave like short Dayem bridges. Using these devices, we have fabricated SQUID magnetometers with galvanically coupled in-plane pickup loops: at T=77K, magnetic field white noise levels as low as 63 fT/Hz have been achieved.