Suppression of Magnetic Flux Noise in YBa2Cu3O7−x Flux Transformers

  • M. J. Ferrari
  • F. C. Wellstood
  • J. J. Kingston
  • M. Johnson
  • J. Clarke
Conference paper
Part of the Springer Proceedings in Physics book series (SPPHY, volume 64)


We have constructed hybrid magnetometers by coupling a flux transformer of YBa2Cu3O7−x to a Nb-Pbln SQUID. The low frequency (1/f) noise is dominated by fluctuations in the supercurrent circulating in the transformer, driven by vortex motion. The application of a small static magnetic field induces a supercurrent that reversibly suppresses the noise, in quantitative agreement with a model of thermally activated vortex hopping between symmetrical pairs of pinning sites. A persistent current can be used to reduce the low frequency noise power of high-Tc flux transformers by at least one order of magnitude.


Noise Power Vortex Motion YBCO Film Persistent Current Field Sensitivity 
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Copyright information

© Springer-Verlag Berlin Heidelberg 1992

Authors and Affiliations

  • M. J. Ferrari
    • 1
    • 2
  • F. C. Wellstood
    • 3
  • J. J. Kingston
    • 1
    • 2
  • M. Johnson
    • 4
  • J. Clarke
    • 1
    • 2
  1. 1.Department of PhysicsUniversity of CaliforniaBerkeleyUSA
  2. 2.Center for Advanced Materials, Materials Sciences DivisionLawrence Berkeley LaboratoryBerkeleyUSA
  3. 3.Center for Superconductivity Research, Department of PhysicsUniversity of MarylandCollege ParkUSA
  4. 4.Bell Communications ResearchRed BankUSA

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