High sensitivity magnetic flux sensors with direct voltage readout: double relaxation oscillation SQUIDs

Author

Adelerhof, D.J. ; Van Duuren, M.J. ; Flokstra, J. ; Rogalla, H. ; Kawai, J. ; Kado, H.

Author_Institution

Dept. of Appl. Phys., Twente Univ., Enschede, Netherlands

Volume

5

Issue

2

fYear

1995

fDate

6/1/1995 12:00:00 AM

Firstpage

2160

Lastpage

2163

Abstract

The experimental sensitivity of double relaxation oscillation SQUIDs (DROSs) has been compared with theory and with the results obtained by numerical simulations. The experimental sensitivity ranges from 60 to 13h, where h is Planck´s constant, for relaxation frequencies from 0.4 up to 10 GHz. For low frequencies the DROS characteristics can be explained by thermal noise on the critical currents. For high frequencies, the voltage-flux characteristics and the sensitivity are limited by the plasma frequency. The cross-over frequency is at 2 GHz, which is about 2% of the plasma frequency of the DROSs.<>

Keywords

SQUID magnetometers; critical currents; digital readout; relaxation oscillators; superconducting device noise; thermal noise; 0.4 to 10 GHz; Planck´s constant; critical currents; cross-over frequency; direct voltage readout; double relaxation oscillation SQUID; high frequencies; high sensitivity magnetic flux sensors; low frequencies the DROS; numerical simulations; plasma frequency; relaxation frequencies; sensitivity; thermal noise; voltage-flux characteristics; Critical current; Damping; Frequency; Hysteresis; Magnetic flux; Magnetic sensors; Plasma properties; Resistors; SQUIDs; Voltage;

fLanguage

English

Journal_Title

Applied Superconductivity, IEEE Transactions on

Publisher

ieee

ISSN

1051-8223

Type

jour

DOI

10.1109/77.403011

Filename

403011