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DOE OSTI · 1473880

Microscale magnetic compasses

Shiozawa, Hidetsugu·Zhang, Desai·Eisterer, Michael·Ayala, Paola·Pichler, Thomas·McCartney, Martha R.·Smith, David J.
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Abstract

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. Finally, 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.

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74 ATOMIC AND MOLECULAR PHYSICS

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Shiozawa, Hidetsugu, Zhang, Desai, Eisterer, Michael, Ayala, Paola, Pichler, Thomas, McCartney, Martha R., Smith, David J.. 2017-09-01. Microscale magnetic compasses. https://doi.org/10.1063/1.4985838

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