A single integral expression for the magnetisation of a textured superparamagnetic system

Cregg, P J and Bessais, Lotfi (1999) A single integral expression for the magnetisation of a textured superparamagnetic system. Journal of Magnetism and Magnetic Materials, 203. pp. 265-267. ISSN 03048853

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Abstract

A superparamagnetic system consists of many single domain particles with relaxation times smaller than the time of measurement (t=100 s), with the result that thermal agitation leads to zero magnetisation in zero field,M(H=0)=0 for t>100 s. For particles in a fluid, an external field will result in a magnetisation given by the Langevin function as inparamagnetism. However, particles fixed into position in the presence of a field, obtain an orientational texture. We still find M(H=0)=0, but the magnetisation is not given by the Langevin function. The model of Chantrell et al. can yield an expression for M capable of including texture. This requires the calculation of the partition function of the system which is a double integral in the coordinate system used. Here we reduce this double integral to a single integral.

Item Type:	Article
Departments or Groups:	Materials Characterisation and Processing Group
Divisions:	School of Engineering > Department of Engineering Technology
Depositing User:	P.J. Cregg
Date Deposited:	12 May 2008 11:35
Last Modified:	22 Aug 2016 10:25
URI:	http://repository-testing.wit.ie/id/eprint/911

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