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

We characterized the current-voltage, voltage-flux, and the field sensitivity of integrated high-Tc series superconducting quantum interference device (SQUID) magnetometers and gradiometers. The series two-SQUID magnetometers shows field sensitivities of ∼30–40 fT/Hz1/2 at 1 kHz and ∼80–100 fT/Hz1/2 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/Hz1/2 cm, while the one-SQUID gradiometer shows a gradient sensitivity of ∼80–150 fT/Hz1/2 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. [ABSTRACT FROM AUTHOR]