A low-noise ferrite magnetic shield

T. W. Kornack, S. J. Smullin, S. K. Lee, M. V. Romalis

Research output: Contribution to journalArticlepeer-review

104 Scopus citations

Abstract

Ferrite materials provide magnetic shielding performance similar to commonly used high permeability metals but have lower intrinsic magnetic noise generated by thermal Johnson currents due to their high electrical resistivity. Measurements inside a ferrite shield with a spin-exchange relaxation-free atomic magnetometer reveal a noise level of 0.75 fT Hz-12, 25 times lower than what would be expected in a comparable μ -metal shield. The authors identify a 1f component of the magnetic noise due to magnetization fluctuations and derive general relationships for the Johnson current noise and magnetization noise in cylindrical ferromagnetic shields in terms of their conductivity and complex magnetic permeability.

Original languageEnglish (US)
Article number223501
JournalApplied Physics Letters
Volume90
Issue number22
DOIs
StatePublished - 2007

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy (miscellaneous)

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