Thin-Film-Based Ultralow Noise SQUID Magnetometer

We report on the development of an ultralow-noise thin-film-based superconducting quantum interference device (SQUID) magnetometer. A niobium thin-film pickup coil is connected to the input coil of a SQUID current sensor. The low capacitance of the used submicrometer cross-type Josephson junctions enables superior noise performance of the device. Application scenarios, e.g., in geophysics and ultralow-field magnetic resonance imaging, are discussed.