Impurity effects and symmetry of the order parameter in high-temperature oxide superconductors

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buir.advisorGedik, Zafer
dc.contributor.authorBayındır, Mehmet
dc.date.accessioned2016-01-08T20:15:07Z
dc.date.available2016-01-08T20:15:07Z
dc.date.issued1997
dc.departmentDepartment of Physicsen_US
dc.descriptionAnkara : Department of Physics and the Institute of Engineering and Science of Bilkent University, 1997.en_US
dc.descriptionThesis (Master's) -- Bilkent University, 1997.en_US
dc.descriptionIncludes bibliographical references leaves 77-90.en_US
dc.description.abstractIdentification of the symmetry of the order parameter (OP) of high-l'c cuprates is important because it helps to understand possible mechanism that govern the physics of these materials. However, up to now, there is no consensus on the symmetry of the OP. On the other hand, nonmagnetic impurity substitutions would test the symmetry of OP. Present theoretical calculations overestimate suppression of the critical temperature (by a factor of 2 or more) in comparison to the experimental data. So far, differences between zinc [Zn) and nickel {Ni) substitutions have not been well understood. Considering the above arguments, effects of nonmagnetic impurities on the high-temperature cuprates are investigated by solving the Bogoliulpv-de Gennes (BdG) equations on two-dimensional square lattice. The critical impurity concentration is found to be very close to the experimental values. Possibility of extracting the symmetry of OP from the obtained results is discussed. Finiteranged impurity potentials and different potential strengths for different impurities are proposed to explain differences between Zn and Ni substitutions. Finally, it is concluded that our results are in favor of d-wave symmetry for tetragonal and s+d-wave symmetry for orthorhombic phase, and explain quite well the effects of nonmagnetic impurity substitutions in the high-7'c oxide superconductors. Beside these, the physical properties of the high-temperature oxide superconductors, the BdG equations and effects of nonmagnetic impurities on isotropic and anisotropic superconductors are reviewed.en_US
dc.description.degreeM.S.en_US
dc.description.statementofresponsibilityBayındır, Mehmeten_US
dc.format.extentxi, 90 leavesen_US
dc.identifier.urihttp://hdl.handle.net/11693/17977
dc.language.isoEnglishen_US
dc.publisherBilkent Universityen_US
dc.rightsinfo:eu-repo/semantics/openAccessen_US
dc.subjectSuperconductivityen_US
dc.subjectorder parameteren_US
dc.subjectimpurity substitutionen_US
dc.subjecthightemperature superconductivityen_US
dc.subjectcritical temperature suppressionen_US
dc.subjects-waveen_US
dc.subjectd-waveen_US
dc.subjectZn or Ni-Cu substitutionen_US
dc.subjectd-|-s-waveen_US
dc.subject.lccQC612.S8 B39 1997en_US
dc.subject.lcshSuperconductivity.en_US
dc.subject.lcshSuperconductors.en_US
dc.subject.lcshHigh temperature superconductivity.en_US
dc.subject.lcshHigh temperature superconductors.en_US
dc.titleImpurity effects and symmetry of the order parameter in high-temperature oxide superconductorsen_US
dc.typeThesisen_US
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