We describe the fabrication and testing of an integrated YBa2Cu3O7−x thin‐film magnetometer consisting of a dc superconducting quantum interference device (SQUID), with biepitaxial grain boundary junctions, integrated with a flux transformer on a single substrate. Only two superconducting layers are required, the SQUID body serving as the crossunder that completes the multiturn flux transformer. The highest temperature at which any of the magnetometers functioned was 76 K. At 60 K the magnetic field gain of this device was 63, and the magnetic field noise was 160 fT Hz−1/2 at 2 kHz, increasing to 3.4 pT Hz−1/2 at 1 Hz.
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© 1993 American Institute of Physics.
1993
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