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Proceedings Paper

A smart nonharmonic magnetic composite with novel sensor applications
Author(s): Ming Yin; Stephen Phillips; Huaizhou Zhang; Michael Wescott; Yuencheol Jeong; Timir Datta; Raphael Tsu
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Paper Abstract

Floatation or levitation, as well as free suspension are intriguing phenomenon. Both require minimum in energy. However, as Lord Kelvin observed only composite systems of diamagnets with permanent and induced magnets can achieve stable equilibrium. Permanent magnets, in contrast to electromagnets retain their ability to attract and hold magnetic objects without any external energy expenditure. This persistent property similar to superconductors is entirely quantum mechanical. Recently M.V. Berry, A.K. Geim and others have re-instigated interest in the stability criteria of these systems. In this work, stability in the horizontal plane is guaranteed by the localization of the holding field. Smart response gives rise to vertical stability. Smartness causes the net force to be repulsive when the object is too close and attractive when far. Here we report for the first time, the production of smart response in a system with diamagnetic and ferromagnetic constituents. The restoring force, F is strongly asymmetric and non-linear with displacement (z); F(z) is non-harmonic, does not follow hook's law. Two types of diamagnetic materials bismuth and pyrolytic graphite were investigated. Consistent with the higher susceptibility, the later provides a factor of two stronger repulsive forces under ambient conditions. Also, for the first time we show that this smart system is extremely un- harmonic. For stable equilibrium, restoring force is essential and sufficient however harmonic behavior is not essential.

Paper Details

Date Published: 12 April 2012
PDF: 9 pages
Proc. SPIE 8409, Third International Conference on Smart Materials and Nanotechnology in Engineering, 840926 (12 April 2012); doi: 10.1117/12.923386
Show Author Affiliations
Ming Yin, Benedict College (United States)
Stephen Phillips, Benedict College (United States)
Huaizhou Zhang, Univ. of South Carolina (United States)
Michael Wescott, Univ. of South Carolina (United States)
Yuencheol Jeong, Univ. of South Carolina (United States)
Timir Datta, Univ. of South Carolina (United States)
Raphael Tsu, The Univ. of North Carolina at Charlotte (United States)

Published in SPIE Proceedings Vol. 8409:
Third International Conference on Smart Materials and Nanotechnology in Engineering
Jinsong Leng; Yoseph Bar-Cohen; In Lee; Jian Lu, Editor(s)

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