Magnetic field behavior of YBCO step-edge Josephson junctions in rf-washer SQUIDs

Author

Bick, M. ; Schubert, J. ; Fardmanesh, M. ; Panaitov, G. ; Banzet, M. ; Zander, W. ; Zhang, Y. ; Krause, H.-J.

Author_Institution

Inst. fur Schicht- und Ionentechnik, Forschungszentrum Julich GmbH, Germany

Volume

11

Issue

1

fYear

2001

fDate

3/1/2001 12:00:00 AM

Firstpage

1339

Lastpage

1342

Abstract

The suppression of the critical current in YBCO Josephson junctions by the Earth´s magnetic field strongly affects the operation of SQUIDs outside magnetic shielding. Commonly, one observes a modulation of the SQUID flux-voltage transfer function amplitude, V_sq-pp, with a period of ΔB_0-v leading to an increased white flux noise level or unstable SQUID operation. Here, we report on the investigation of ΔB_0-v of rf-SQUID sensors based on step edge junctions (SEJ) operated in a flip chip configuration with coplanar resonators with integrated flux concentrators. To investigate the origin of the suppression of V_sq-pp, we opened the SQUID loop of some samples and measured the magnetic field dependence of the critical current I_c(B) directly and compared it to V_sq-pp(B). It is shown that a junction width in the submicrometer scale is required for operation of the sensors in the Earth´s magnetic field

Keywords

Josephson effect; SQUIDs; barium compounds; critical currents; high-temperature superconductors; superconducting device noise; white noise; yttrium compounds; Earth magnetic field; LaAlO₃; SQUID flux-voltage transfer function amplitude modulation; SQUID loop; YBa₂Cu₃O₇; YBaCuO step-edge Josephson junctions; coplanar resonators; critical current suppression; flip chip configuration; integrated flux concentrators; magnetic field behavior; magnetic field dependence; magnetic shielding; rf-washer SQUIDs; submicrometer scale junction width; unstable SQUID operation; white flux noise level; Amplitude modulation; Critical current; Earth; Josephson junctions; Magnetic field measurement; Magnetic fields; Magnetic sensors; Magnetic shielding; SQUIDs; Yttrium barium copper oxide;

fLanguage

English

Journal_Title

Applied Superconductivity, IEEE Transactions on

Publisher

ieee

ISSN

1051-8223

Type

jour

DOI

10.1109/77.919598

Filename

919598