Integrated high-transition temperature squid-based voltmeters operated at 77 k

Hong-Chang Yang, J. H. Chen, Herng-Er Horng, Shieh-Yueh Yang, J. T. Jen

Research output: Contribution to journalArticle

Abstract

The voltage noise levels of high-Tc based YBa2Cu3Oy bicrystal SQUIDs and SQUID voltmeters were measured to investigate their noise characteristics. The SQUIDs are of washer type with outer dimension of 90 μm × 90 μm and inner dimension of 20 urn x 20 um. The SQUIDs have a normal inductance of about 60 pH. The integrated modulation and input coils were circular in shape. The modulation coil has a radius of r2 = 80 u.m and r, = 60 [im while the input coil for voltage measurement has radius r, = 50 urn and r, =30 (im. Using a dc bias and standard flux locked loop, the spectral density of the voltage noise, Sv, was observed to behave as I/fat low frequencies and the root mean square flux noise, S2, is white and has a value of ~15 nO0/Hz2 at l kHz. The flux noise levels were reduced to ~ 4 ii-4yHz2 using the ac bias reversing technique. These data suggest that the dominant 1/f voltage noise was caused by critical current fluctuations. We further demonstrate that the 1/f can be induced by flux motion. The voltage noise levels of the SQUID voltmeters are also reported.

Original languageEnglish
Pages (from-to)4412-4415
Number of pages4
JournalIEEE Transactions on Applied Superconductivity
Volume9
Issue number2 PART 3
DOIs
Publication statusPublished - 1999 Dec 1

Fingerprint

Voltmeters
voltmeters
SQUIDs
Superconducting transition temperature
transition temperature
Fluxes
Electric potential
coils
electric potential
Modulation
Bicrystals
Washers
Spectral density
Critical currents
Voltage measurement
Oils and fats
washers
Inductance
modulation
radii

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering

Cite this

Integrated high-transition temperature squid-based voltmeters operated at 77 k. / Yang, Hong-Chang; Chen, J. H.; Horng, Herng-Er; Yang, Shieh-Yueh; Jen, J. T.

In: IEEE Transactions on Applied Superconductivity, Vol. 9, No. 2 PART 3, 01.12.1999, p. 4412-4415.

Research output: Contribution to journalArticle

Yang, Hong-Chang ; Chen, J. H. ; Horng, Herng-Er ; Yang, Shieh-Yueh ; Jen, J. T. / Integrated high-transition temperature squid-based voltmeters operated at 77 k. In: IEEE Transactions on Applied Superconductivity. 1999 ; Vol. 9, No. 2 PART 3. pp. 4412-4415.
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