Microscale magnetic compasses

Microscale magnetic compasses have been synthesized with high yield. These ferromagnetic iron carbide nano-particles, which are encapsulated in a pair of parallel carbon needles, change their orientation in response to an external magnetic field. Electron holography reveals magnetic fields confined...

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Bibliographic Details
Published in:Journal of applied physics 2017-09, Vol.122 (9)
Main Authors: Shiozawa, Hidetsugu, Zhang, Desai, Eisterer, Michael, Ayala, Paola, Pichler, Thomas, McCartney, Martha R., Smith, David J.
Format: Article
Language:English
Subjects:
Anisotropy
ATOMIC AND MOLECULAR PHYSICS
Compasses
Demagnetization
Electromagnetic radiation
Encapsulation
Ferromagnetism
Holography
Iron carbides
Magnetic compasses
Magnetic domains
Magnetic fields
Magnetic permeability
Magnetorheological fluids
Needles
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Summary:Microscale magnetic compasses have been synthesized with high yield. These ferromagnetic iron carbide nano-particles, which are encapsulated in a pair of parallel carbon needles, change their orientation in response to an external magnetic field. Electron holography reveals magnetic fields confined to the vicinity of the bicone-shaped particles, which are composed of only a few ferromagnetic domains. Aligned magnetically and encapsulated in an acrylate polymer matrix, these micro-compasses exhibit anisotropic bulk magnetic permeability with an easy axis normal to the needle direction that can be understood as a result of the anisotropic demagnetizing field of a non-spherical single-domain particle. This novel type of material with orthogonal magnetic and structural axes could be highly useful as magnetic components in electromagnetic wave absorbent materials and magnetorheological fluids.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.4985838