We report on a novel integrated magnetometer concept that combines inductance matching by a flux transformer with the low inductance of a multiloop pick‐up coil. A 90 pH dc superconducting quantum interference device together with a five turn flux transformer is coupled to a multiloop pick‐up coil resulting in an effective magnetometer area of 1.4 mm2 on a 10×10 mm2 substrate. Using ramp‐type Josephson junctions with PrBa2Cu3O7 barriers, a white noise level of √SB(1 kHz) = 44 fT/√Hz is measured. The 1/f‐flux noise of the integrated magnetometer is suppressed successfully by operation in a flux‐locked loop mode with bias current modulation. At 77 K we find a flux density noise of √SB(1 Hz) = 100 fT/√Hz.

Topics
Superconducting quantum interference device, High temperature superconductors, Magnetic equipment, Superconducting devices, Transformer, Signal processing
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