A low-noise ferrite magnetic shield
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TLDR
In this paper, the authors identify a 1∕f 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.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 0.75fTHz−1∕2, 25 times lower than what would be expected in a comparable μ-metal shield. The authors identify a 1∕f 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.read more
Citations
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Ultra-high sensitivity magnetic field and magnetization measurements with an atomic magnetometer
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Ultrahigh sensitivity magnetic field and magnetization measurements with an atomic magnetometer
TL;DR: In this article, the authors describe an ultra-sensitive atomic magnetometer based on optically pumped potassium atoms operating in a spin exchange relaxation free regime, and demonstrate magnetic field sensitivity of 160 εaT/Hz1/2 in a gradiometer arrangement with a measurement volume of 0.45 cm3 and energy resolution per unit bandwidth of 44ℏ.
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Spin-exchange relaxation-free magnetometry using elliptically polarized light
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References
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Experimental Observation of Optical Rotation Generated in Vacuum by a Magnetic Field
E. Zavattini,Guido Zavattini,Giuseppe Ruoso,E. Polacco,Edoardo Milotti,Marin Karuza,U. Gastaldi,G. Di Domenico,F. Della Valle,Roberto Cimino,S. Carusotto,G. Cantatore,Marco Bregant +12 more
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Effects of spin-exchange collisions in a high-density alkali-metal vapor in low magnetic fields
Igor Savukov,Michael Romalis +1 more
TL;DR: In this article, a detailed study of the Zeeman resonance frequencies and linewidths as a function of the magnetic field, alkali-metal density, and the degree of spin polarization of the atoms is presented.