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Monte Carlo Study of the Magnetic Flux Lattice Fluctuations in High-<em>T<sub>c</sub></em> Superconductors

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dc.contributor.authorBeny, Cedricen
dc.date.accessioned2006-08-22T14:42:17Z
dc.date.available2006-08-22T14:42:17Z
dc.date.issued2005en
dc.date.submitted2005en
dc.description.abstractBy allowing to measure the magnetic field distribution inside a material, muon spin rotation experiments have the potential to provide valuable information about microscopic properties of high-temperature superconductors. Nevertheless, information about the intrinsic superconducting properties of the material is masked by random thermal and static fluctuations of the magnetic field which penetrates the material in the form of vortices of quantized magnetic flux. A good understanding of the fluctuations of those vortices is needed for the correct determination of intrinsic properties, notably the coherence length &xi;, and the field penetration depth &lambda;. We develop a simulation based on the Metropolis algorithm in order to understand the effect, on the magnetic field distribution, of disorder- and thermally-induced fluctuations of the vortex lattice inside a layered superconductor. <br /><br /> Our model correctly predicts the melting temperatures of the YBa<sub>2</sub>Cu<sub>3</sub>O<sub>6. 95</sub> (YBCO) superconductor but largely underestimates the observed entropy jump. Also we failed to simulate the high field disordered phase, possibly because of a finite size limitation. In addition, we found our model unable to describe the first-order transition observed in the highly anisotropic Bi<sub>2</sub>Sr<sub>2</sub>CaCu<sub>2</sub>O<sub>8+<em>y</em></sub>. <br /><br /> Our model predicts that for YBCO, the effect of thermal fluctuations on the field distribution is indistinguishable from a change in &xi;. It also confirms the usual assumption that the effect of static fluctuations at low temperature can be efficiently modeled by convolution of the field distribution with a Gaussian function. However the extraction of &xi; at low fields requires a very high resolution of the field distribution because of the low vortex density.en
dc.formatapplication/pdfen
dc.format.extent3602128 bytes
dc.format.mimetypeapplication/pdf
dc.identifier.urihttp://hdl.handle.net/10012/1222
dc.language.isoenen
dc.pendingfalseen
dc.publisherUniversity of Waterlooen
dc.rightsCopyright: 2005, Beny, Cedric. All rights reserved.en
dc.subjectPhysics & Astronomyen
dc.subjecthigh temperature superconductoren
dc.subjectflux line lattice meltingen
dc.subjectmagnetic vorticesen
dc.subjectmuon spin rotationen
dc.subjectMonte Carlo simulationen
dc.subjectcoherence lengthen
dc.subjectpenetration depthen
dc.subjectentropy jumpen
dc.subjectYBCOen
dc.titleMonte Carlo Study of the Magnetic Flux Lattice Fluctuations in High-<em>T<sub>c</sub></em> Superconductorsen
dc.typeMaster Thesisen
uws-etd.degreeMaster of Scienceen
uws-etd.degree.departmentPhysicsen
uws.peerReviewStatusUnrevieweden
uws.scholarLevelGraduateen
uws.typeOfResourceTexten

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