Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 17 of 17 for “"BCS-theory"”.
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Investigation of superconducting order parameters in heavy-fermion and low-dimensional metallic systems under pressure
… in 1911, prior to the development of the quantum theory of matter, superconductivity was defying a microscopic theory for more than four decades until the BCS theory was formulated in 1957 by J. Bardeen, L. N. Cooper and J. R. Schrieffer. Superconductivity of most of the simple metals or metallic …
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Aspects of superconductivity and fractionalization
Since their discovery in mid 80's, a complete theory of high temperature superconductors is yet to take its final shape. Theory of fractionalization attempts to explain the phenomenon by assuming that the electron is split into two particles, chargon and spinon, carrying charge and spin …
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Raman Scattering From the Superconductor Niobium-Diselenide
… phonon self energy is calculated using the BCS theory for the electrons.
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A study of vortex lattices and pulsar glitches
… the phenomenon of superconductivity: The London theory, the Ginzburg-Landau theory and the BCS theory. We review works by several authors who utilized these theories as the basis for their investigation. In our literature review we study the behavior of single and multivortex states in mesoscopic …
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Heat capacity measurements of yttrium barium(2)copper(3)oxygen(7-delta) near T(c): Fluctuation effects in a bulk superconductor
… both as a lowest-order correction to mean-field BCS theory (the Gaussian approximation) and in terms of true critical behavior. The analysis shows that the data are best described within the Gaussian approximation as three-dimensional fluctuations of a two-component order parameter, but the …
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Investigation of the deformed fermi surfaces mechanism for pairing of two species of fermions with mismatched fermi surfaces
… Then within the frame work of the weak-coupling BCS theory, the expectation value of the Hamiltonian of a conductor under an exchange or Zeeman field is derived, from which a gap equation is derived by differentiation. The influence of deformed Fermi surfaces on the chemical potential is then …
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Critical magnetic fields of superconducting tungsten
… is in good agreement with the weak-coupling BCS theory. The very small calculated Ginzburg-Landau parameter (x:: 2 X 10^-3 ) and extremely large calculated coherence length (~o ~ 32u) are favorable for observation of a large supercooling effect in tungsten at temperatures well below Tc. …
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Extraction of Spin Polarization of Bulk and Measurement of Transport Properties of Thin GdxSi1-x Near the Metal-Insulator Transition
Since the early 1960s, Abrikosov-Gorkov theory has been used to describe superconductors with paramagnetic impurities. Interestingly, the density of states resulting from the theoretical framework has to date only been known approximately, as a numeric solution of a complex polynomial. An …
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Electronic and lattice vibrational properties of thorium hydrides
… deviate appreciably from the predictions of the BCS theory. Both the normalized specific heat discontinuity at Tc and the ratio of the energy gap to Tc are comparable to those of other weak-coupled superconductors. A re1ative1y large electronic density of states at the Fermi level suggests the …
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Computational Modeling of Superconductivity from the Set of Time-Dependent Ginzburg-Landau Equations for Advancements in Theory and Applications
… the dynamics of superconductors in various theory revealing states and practical purposes. A review of the history and phenomenon of superconductivity, including modern applications, is introduced. The Josephson effect and associated Josephson junction are discussed for comparison to our …
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Physics of Superconducting Travelling-Wave Parametric Amplifiers
… which are derived from the microscopic BCS theory. I investigate the supercurrent nonlinearity that is intrinsic to the physics of superconductors, and calculate its effect on the electrodynamics of superconducting materials. At component-level, I develop electromagnetic models for …
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Enhancement of superconductivity in Magnesium Diboride nano-structures
… field approach (Bardeen- Cooper-Schrieffer or BCS theory) and tried to extend the model presented by Thompson and Blatt of a one-band superconductor thin film to the case of a two-band superconductor thin film. The most relevant results of this research are: for an infinite thin film with a …
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Nuclear magnetic resonance studies of YBa2̳Cu3̳07̳ in the superconducting state
… within a generalized Bardeen-Cooper-Schrieffer (BCS) pairing theory, and find that a spin-singlet pairing state is strongly favored by these data. The temperature dependence of the Cu(l) Knight shift is slightly different from the temperature dependence of the Cu(2) Knight shift. It is possible …
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Low Field Microwave Absorption in Nano-Magnetic Participle - incorporated YBa2Cu3O7-z Superconducting Materials
… the major milestones, such as the London theory, the Landau-Ginzburg theory, and the BCS theory. The extreme challenge to predict the occurrence of SC is symbolized by the long string of unanticipated but breathtaking advances, i.e., the unexpected discoveries of cuprates and Fe-pnictides …
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Probing nano-scale atomic and electronic structures of iron-based superconductors
… high Tc that the Bardeen-Cooper-Schrieffer (BCS) theory of superconductivity has failed to predict. Furthermore, the iron-based high-Tc superconductors demonstrate intrinsic properties that are distinct from the cuprates, including a different pairing symmetry, coexistence of superconducting …
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Phenomenological phase-fluctuation model for the underdoped cuprates
… in this thesis consists of a two-dimensional BCS-like Hamiltonian where the phase of the pairing-amplitude is free to fluctuate. The fluctuations of the phase were treated by a Monte Carlo simulation of a classical XY model. First, the density of states was calculated. The quasiparticle …
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Exact Results on Extended Hubbard Models on One-Dimensional Chains
… superconductors suggested that a microscopic theory of this phenomenon could be formulated in terms of electron-electron interaction, without explicitly invoking the phonon coupling, like in BCS theory. Although an exhaustive microscopic formulation for cuprate superconductivity has not been …