Characteristics of integrated high-T_c superconducting quantum interference device magnetometer and gradiometer with serial array

摘要

We characterized the current-voltage, voltage-flux, and the field sensitivity of integrated high-T_c series superconducting quantum interference device (SQUID) magnetometers and gradiometers. The series two-SQUID magnetometers shows field sensitivities of ～30-40 fT/Hz~(1/2) at 1 kHz and ～80-100 fT/Hz~(1/2) at 1 Hz over that of a one-SQUID magnetometer in shielded environment. The field sensitivity of a series two-SQUID gradiometers is ～60 fT/Hz~(1/2) cm, while the one-SQUID gradiometer shows a gradient sensitivity of ～80-150 fT/Hz~(1/2) cm at 1 kHz in an unshielded laboratory environment. The series two-SQUID magnetometers or gradiometers show a significant improvement in flux noises over that of one-SQUID magnetometers or gradiometers.