Magnetometers based on double relaxation oscillation superconducting quantum interference devices (SQUIDs) (DROSs) have been fabricated and characterized. The DROSs are based on 2×2μm2Nb/AlOx tunnel junctions and have a 25 turn, tightly coupled input coil. The high flux-to-voltage transfer coefficient of 1-2mV/φ0 facilitates direct voltage readout by a low-noise dc amplifier. The pickup coil consists of a thin-film Nb gradiometer with a baseline of 40 mm and an inductance of 110 nH. The white field noise of the magnetometer was better than 5 ft/Hz, which is sufficient for magnetoencephalography measurements.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)