Improvement of Sensitivity of a Compact Magnetometer by Using HTS‐SQUID with Rotating Sample

SUMMARY We have improved a previously developed compact magnetometer using HTS-SQUID with a rotating sample. In the previous system, attenuation of the rotational speed had resulted in deformation of the averaged waveform signal, reducing the reproducibility of measurements. In this paper, we have used a better motor in order to decrease the attenuation of the rotational speed for precise averaging of the output signal and improvement of the signal-to-noise ratio. To improve sensitivity, we also optimized the pickup coil and compared the signal-to-noise ratio of circular and elliptical pickup coils having the same number of turns, resistance, and inductance. As a result, the signal-to-noise ratio was improved with high accuracy and the magnetometer showed a susceptibility sensitivity of 3.8× 10−9 emu.