HIGH-TC DC SQUID MAGNETOMETER WITH A SERIES ARRAY

Superconducting quantum interference device (SQUID) magnetometers have been fabricated from series arrays of YBa2Cu3O7 dc SQUIDs by pulsed-l aser film deposition and ion-mill-patterning techniques. The array was designed either in a linear chain with flux focusers or in a meander structure. The arrays consisted of 50 similar to 130 step-edge junctio n SQUIDs, and each SQUID had an inductance of 20 similar to 40 pH and a,junction width of 2 similar to 5 mu m. A 50-SQUID linear array showe d a modulation amplitude of 150 V, which corresponds to a gain of simi lar to 10. One of the 80-SQUID meander arrays has shown a gain of 50. These results demonstrate the feasibility of using a series array of S QUIDs in direct readout SQUID amplifier circuitry with a wide bandwidt h. Larger number SQUID arrays and processes to increase the gain to th e theoretical value need to be studied.