Show simple item record

dc.contributor.authorCOFFEY, WILLIAM THOMAS
dc.date.accessioned2009-06-17T16:47:30Z
dc.date.available2009-06-17T16:47:30Z
dc.date.issued1996
dc.date.submitted1996en
dc.identifier.citationCoffey, W.T., Crothers, D.S.F., 'Comparison of methods for the calculation of superparamagnetic relaxation times' in Physical Review E - Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics, 54, 5, (1996), pp 4768 - 4774en
dc.identifier.otherY
dc.identifier.otherYen
dc.identifier.urihttp://hdl.handle.net/2262/30609
dc.descriptionPUBLISHEDen
dc.description.abstractA general expression for the correlation time of the decay of the magnetization of an assembly of singledomain noninteracting ferromagnetic particles is given in terms of the inverse of the Fokker-Planck operator. The results of Moro and Nordio [G. Moro and P. L. Nordio, Mol. Phys. 56, 255 (1985)], given in the context of dielectric relaxation, are recovered when the Fokker-Planck operator is axially symmetric. Their result is a particular example of Szabo's calculation of the correlation times of the autocorrelation functions of the Legendre polynomials by means of a generalization of the theory of first-passage times [A. Szabo, J. Chem. Phys. 72, 4620 (1980)]. Likewise, the results of Garanin, Ischenko, and Panina (D. A. Garanin, V. V. Ischenko, and L. V. Panina, Teor. Mat. Fiz. 82, 242 (1990) [Theor. Math. Phys. 82, 169 (1990)]) for the integral relaxation time, i.e., the area under the curve of the normalized decay of the magnetization, are regained in the axially symmetric case where it is possible to integrate the Fokker-Planck equation directly. It is shown by manipulation of Kummer's functions that the exact integral expression for the correlation time for simple uniaxial anisotropy derived by Coffey et al. [W. T, Coffey, D. S. F. Crothers, Yu. P. Kalmykov, E. S. Massawe, and J. T. Waldron. Phys. Rev. E 49, 1869 (1994)] by representing the Fokker-Planck equation as a differential-recurrence relation is identical to the integral relaxation time originally derived by Garanin et al. by direct integration of the Fokker-Planck equation.en
dc.description.sponsorshipWe would like to thank the British Council, Forbairt, and the Trinity College Dublin Trust for grants in support of this work. D.S.F.C. acknowledges the United Kingdom SERC Rolling Grant No. GR/K24741. We thank Dr. Yuri P. Kalmykov and Dr. J. T. Waldron for helpful conversations.en
dc.format.extent4768en
dc.format.extent4774en
dc.format.extent150623 bytes
dc.format.mimetypeapplication/pdf
dc.language.isoenen
dc.publisherAmerican Physical Societyen
dc.relation.ispartofseriesPhysical Review E - Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topicsen
dc.relation.ispartofseries54en
dc.relation.ispartofseries5en
dc.rightsYen
dc.subjectElectronic & Electrical Engineeringen
dc.titleComparison of methods for the calculation of superparamagnetic relaxation timesen
dc.typeJournal Articleen
dc.type.supercollectionscholarly_publicationsen
dc.type.supercollectionrefereed_publicationsen
dc.identifier.peoplefinderurlhttp://people.tcd.ie/wcoffey
dc.identifier.rssinternalid32118


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record