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dc.contributor.advisorDavid G. Cory and Leonid S. Levitov.en_US
dc.contributor.authorGreenbaum, Danielen_US
dc.contributor.otherMassachusetts Institute of Technology. Dept. of Physics.en_US
dc.date.accessioned2006-03-29T18:42:45Z
dc.date.available2006-03-29T18:42:45Z
dc.date.copyright2005en_US
dc.date.issued2005en_US
dc.identifier.urihttp://hdl.handle.net/1721.1/32417
dc.descriptionThesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2005.en_US
dc.descriptionIncludes bibliographical references (p. 87-90).en_US
dc.description.abstractWe have studied the transport of magnetization and energy in systems of spins 1/2 on a lattice at high temperature. This work was motivated by recent experiments which observed "spin diffusion" among the dipolar coupled nuclear spins of the insulator calcium fluoride, under conditions where it was appropriate to neglect the coupling to any heat reservoir. The dynamics under these conditions is coherent and reversible, yet signatures of irreversibility (i.e. diffusion) are typically observed. This state of affairs poses a formidable conceptual puzzle. In this thesis we present both phenomenological and microscopic models of spin diffusion, retaining the important aspects of statistical approaches to transport while incorporating relevant quantum effects. These methods allow an efficient calculation of energy diffusion for a long- range interaction, which has largely been an intractable problem. We study transport in two different limits, that where the XY term of the spin Hamiltonian is dominant, and that where it can be treated as a perturbation compared to the Ising term. In the case of dipolar couping, both limits are found to show slightly more rapid diffusion of inter spin energy than magnetization, in qualitative agreement with experiments.en_US
dc.description.statementofresponsibilityby Daniel Greenbaum.en_US
dc.format.extent90 p.en_US
dc.format.extent3705976 bytes
dc.format.extent3710254 bytes
dc.format.mimetypeapplication/pdf
dc.format.mimetypeapplication/pdf
dc.language.isoengen_US
dc.publisherMassachusetts Institute of Technologyen_US
dc.rightsM.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.en_US
dc.rights.urihttp://dspace.mit.edu/handle/1721.1/7582
dc.subjectPhysics.en_US
dc.titleQuantum spin transport in paramagnetic systemsen_US
dc.typeThesisen_US
dc.description.degreePh.D.en_US
dc.contributor.departmentMassachusetts Institute of Technology. Dept. of Physics.en_US
dc.contributor.departmentMassachusetts Institute of Technology. Department of Physics
dc.identifier.oclc61697858en_US


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