Monolithic flux transformer-coupled high-Tc DC SQUID magnetometers

摘要

YBa2Cu3O7-x based monolithic flux transformer-coupled high-Tc DC SQUID magnetometers operating up to 73 K have been realized. The devices are characterized by high values of the modulation voltage, up to 32 μV at 40 K. A minimal white noise level of 0.10 pT/√Hz was obtained above 200 Hz, and 0.64 pT/√Hz at 1 Hz and 55 K. The temperature dependence of the modulation voltage, the effective sensing area and the field sensitivity are discussed. Model-calculations have been performed to investigate high frequency resonances in the washer-input coil structure. Methods for damping are considered.