Noise properties of direct current SQUIDs with quasiplanar YBa2Cu3O7 Josephson junctions
نویسندگان
چکیده
We describe the noise performance of dc SQUIDs fabricated with quasiplanar ramp-type Josephson junctions on the basis of c-axis-oriented YBa2Cu3O7 /PrBa2Cu3O7 thin-film heterostructures. The noise spectrum of the dc SQUIDs was measured with dcand ac-bias schemes at different temperatures and showed values below 10 F0 /Hz 1/2 down to frequencies of about 1 Hz at 70 K. Up to now for the magnetic flux noise and the energy resolution obtained at 1 kHz and 77 K the best values were 2.5310, F0 /Hz 1/2 and 3310 J/Hz, respectively. A study of the white and 1/f noises of the SQUIDs was performed. The influence of magnetic flux, bias current, high static magnetic fields, and aging on the SQUID noise were investigated. The junctions and devices do not degrade due to aging in air or thermal cycling. © 1995 American Institute of Physics.
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تاریخ انتشار 2015