Crystal growth and neutron scattering studies of high temperature superconductors
Item
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Title
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Crystal growth and neutron scattering studies of high temperature superconductors
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Identifier
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d_2009_2013:41777b789220:10952
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identifier
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11243
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Creator
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Xu, Zhijun,
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Contributor
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J. J. Tu | G. Gu | J. M. Tranquada
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Date
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2011
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Language
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English
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Publisher
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City University of New York.
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Subject
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Condensed matter physics | Crystal Growth | Neutron Scattering | Superconductivity
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Abstract
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Since the discovery of the first high temperature superconductor in the 1980's, there have been continuing efforts to understand the mechanism of high-TC superconductivity. Studies on the cuprate systems seem to suggest that there is an intimate relationship between superconductivity and magnetism, and recently this has also shown to be the case for the newly discovered Fe-based superconductors. Neutron scattering is a powerful tool for studying magnetism in superconductors, which can provide important information about the momentum and energy dependence of magnetic correlations.;The work presented in this thesis is divided into two main sections. Since high-quality large-size single crystals are necessary for the neutron scattering experiments. The first section is about sample preparation, where I will introduce single crystal growths via the Floating-zone technique as well as unidirectional solidification methods. The second section is neutron scattering experiments, which will show neutron scattering and transport measurements results in two high-temperature superconductor systems: La2-xBaxCuO4 (LBCO), and Fe1+yTe1- xSex (FeTeSe). In the LBCO system, we found that static magnetic order competes with bulk superconductivity. In addition, applying a magnetic field to or adding Zn impurities in the sample will enhance the static magnetic order and suppress the superconductivity. In the FeTeSe system, we found that spin resonance is associated with superconductivity, while resonance and superconductivity are simultaneously suppressed by an applied magnetic field or adding Fe impurities. Our results suggest that the magnetic correlations are important for the superconductivity, and proper tuning of these correlations may be a key for superconductivity.
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Type
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dissertation
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Source
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2009_2013.csv
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degree
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Ph.D.
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Program
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Physics
