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dc.contributor.authorCOFFEY, WILLIAM THOMAS
dc.contributor.authorKALYMYKOV, YURI PETROVICH
dc.date.accessioned2009-06-17T09:52:06Z
dc.date.available2009-06-17T09:52:06Z
dc.date.issued2008
dc.date.submitted2008en
dc.identifier.citationKalmykov, Y.P., Coffey, W.T., Titov, S.V., 'Phase-space equilibrium distributions and their applications to spin systems with nonaxially symmetric Hamiltonians' in Physical Review B - Condensed Matter and Materials Physics, 77, 10, (2008), art. no. 104418en
dc.identifier.otherY
dc.identifier.otherYen
dc.identifier.urihttp://hdl.handle.net/2262/30527
dc.descriptionPUBLISHEDen
dc.description.abstractThe Fourier series representation of the equilibrium quasiprobability density function WS(theta,phi) or Wigner function of spin ?orientations? for arbitrary spin Hamiltonians in a representation (phase) space of the polar angles (theta,phi) (analogous to the Wigner function for translational motion) arising from the generalized coherent state representation of the density operator is evaluated explicitly for some nonaxially symmetric problems including a uniaxial paramagnet in a transverse external field, a biaxial, and a cubic system. It is shown by generalizing transition state theory to spins [i.e., calculating the escape rate using the equilibrium density function WS(theta,phi) only] that one may evaluate the reversal time of the magnetization. The quantum corrections to the transition state theory escape rate equation for classical magnetic dipoles appear both in the prefactor and in the exponential part of the escape rate and exhibit a marked dependence on the spin number. Furthermore, the phase-space representation allows us to estimate the switching field curves and/or surfaces for spin systems because quantum effects in these fields can be estimated via Thiaville's geometrical method [Phys. Rev. B 61, 12221 (2000)] for the study of the magnetization reversal of single-domain ferromagnetic particles. The calculation is accomplished (just as the determination of the equilibrium quasiprobability distributions in the phase space of the polar angles) by calculating switching field curves and/or surfaces using the Weyl symbol (c-number representation) of the Hamiltonian operator for given magnetocrystalline-Zeeman energy terms. Examples of such calculations for various spin systems are presented. Moreover, the reversal time of the magnetization allows us to estimate thermal effects on the switching fields for spin systems.en
dc.description.sponsorshipThis publication has emanated from research conducted with the financial support of Science Foundation Ireland Project No. 05/RFP/PHY/0070. We thank Derrick S. F. Crothers, P.-M. Dejardin, and Bernard P. J. Mulligan for helpful conversations.en
dc.format.extentart. no. 104418en
dc.format.extent440372 bytes
dc.format.mimetypeapplication/pdf
dc.language.isoenen
dc.publisherAmerican Institute of Physicsen
dc.relation.ispartofseriesPhysical Review B - Condensed Matter and Materials Physicsen
dc.relation.ispartofseries77en
dc.relation.ispartofseries10en
dc.rightsYen
dc.subjectElectronic & Electrical Engineeringen
dc.titlePhase-space equilibrium distributions and their applications to spin systems with nonaxially symmetric Hamiltoniansen
dc.typeJournal Articleen
dc.contributor.sponsorScience Foundation Ireland
dc.type.supercollectionscholarly_publicationsen
dc.type.supercollectionrefereed_publicationsen
dc.identifier.peoplefinderurlhttp://people.tcd.ie/wcoffey


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