A planar YBa2Cu3O7 gradiometer at 77 K

✍ Scribed by S. Knappe; D. Drung; T. Schurig; H. Koch; M. Klinger; J. Hinken

• Publisher: Elsevier Science
• Year: 1992
• Tongue: English
• Weight: 538 KB
• Volume: 32
• Category: Article
• ISSN: 0011-2275
• DOI: 10.1016/0011-2275(92)90354-d

✦ Synopsis

We describe the fabrication and performance of a single-layer YBa2Cu307 (YBCO) d.c. SQUID in a first-order gradiometer configuration. The junctions are of the step-edge type. The edge formation in the MgO substrate and all patterning were performed by Ar-plasma etching utilizing standard photoresist masks, thus involving more common and simpler fabrication techniques than reported by other groups. The gradiometer consists of two 1.2 mm 2 pick-up coils with a baseline of 1.7 mm coupled directly to a 90 x 90/xm 2 SQUID loop. At 77 K a total white noise of 185/dI o Hz -1/2 and a 1If corner of about 10 Hz have been measured. This corresponds to an intrinsic flux noise level of about 70/~o Hz-1/2, an energy sensitivity of 6.3 x 10 -29 J Hz-1 and a gradient noise level of 2.2 nT m-1 Hz-1/2