Properties of grooved Dayem bridge based YBa_2Cu_3O_(7-δ) superconducting quantum interference devices and magnetometers

摘要

The transport properties of a YBa_2Cu_3O_(7-δ) superconducting quantum interference device (SQUID) based on grooved Dayem bridge weak links are studied as a function of temperature: at high temperatures (60 K ＜ T ＜ T_c = 89 K), the weak links show properties similar to superconductor-normal conductor-superconductor junctions, while at temperatures below 60 K, 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)~(1/2) have been achieved.