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Articles 1 - 6 of 6
Full-Text Articles in Physics
Charge Instabilities And Phase-Separation In 3-Band Extended Hubbard Models: Effect Of O-O Hopping, N. Kothekar, K. F. Quader, David W. Allender
Charge Instabilities And Phase-Separation In 3-Band Extended Hubbard Models: Effect Of O-O Hopping, N. Kothekar, K. F. Quader, David W. Allender
David W Allender
We explore the interplay between various interaction and hopping terms, in particular the effect of O-O hopping, tppo on the charge instabilities and phase separation in the three-band extended Hubbard models. Within a weak-coupling mean-field approach, we find that in two dimensions (2D), tppo moves the phase separation boundary appreciably to higher dopings. This would increase the window of doping over which charge-transfer-mediated superconductivity can occur. Considering a larger phase space, we also obtain a more complete picture of the coexistence lines and spinodal decompositions, and determine the charge-transfer-instability critical point. We also consider the 1D case: tppo is found …
Multiband S -Wave Topological Superconductors: Role Of Dimensionality And Magnetic Field Response, Shusa Deng, Gerardo Ortiz, Lorenza Viola
Multiband S -Wave Topological Superconductors: Role Of Dimensionality And Magnetic Field Response, Shusa Deng, Gerardo Ortiz, Lorenza Viola
Dartmouth Scholarship
We further investigate a class of time-reversal-invariant two-band s-wave topological superconductors introduced earlier [Deng, Viola, and Ortiz, Phys. Rev. Lett. 108, 036803 (2012)]. Provided that a sign reversal between the two superconducting pairing gaps is realized, the topological phase diagram can be determined exactly (within mean field) in one and two dimensions as well as in three dimensions upon restricting to the excitation spectrum of time-reversal-invariant momentum modes. We show how, in the presence of time-reversal symmetry, Z2 invariants that distinguish between trivial and nontrivial quantum phases can be constructed by considering only one of the Kramers’ sectors …
Vortex Physics In Confined Geometries, M. Cristina Marchetti, David R. Nelson
Vortex Physics In Confined Geometries, M. Cristina Marchetti, David R. Nelson
David R. Nelson
Patterned irradiation of cuprate superconductors with columnar defects allows a new generation of experiments which can probe the properties of vortex liquids by forcing them to flow in confined geometries. Such experiments can be used to distinguish experimentally between continuous disorder-driven glass transitions of vortex matter, such as the vortex glass or the Bose glass transition, and nonequilibrium polymer-like glass transitions driven by interaction and entanglement. For continuous glass transitions, an analysis of such experiments that combines an inhomogeneous scaling theory with the hydrodynamic description of viscous flow of vortex liquids can be used to infer the critical behavior. After …
High Pressure Studies Of Superconductivity, Narelle Jayne Hillier
High Pressure Studies Of Superconductivity, Narelle Jayne Hillier
All Theses and Dissertations (ETDs)
Superconductivity has been studied extensively since it was first discovered over 100 years ago. High pressure studies, in particular, have been vital in furthering our understanding of the superconducting state. Pressure allows researchers to enhance the properties of existing superconductors, to find new superconductors, and to test the validity of theoretical models. This thesis presents a series of high pressure measurements performed in both He-gas and diamond anvil cell systems on various superconductors and on materials in which pressure-induced superconductivity has been predicted. Under pressure the alkali metals undergo a radical departure from the nearly-free electron model. In Li this …
Imaging The Anisotropic Nonlinear Meissner Effect In Nodal Yba ₂Cu₃O7-Δ Thin-Film Superconductors, Alexander P. Zhuravel, Behnood G. Ghamsari, Cihan Kurter, Philipp Jung, Stephen K. Remillard, John A. Abrahams, Alexander V. Lukashenko, Alexey V. Ustinov, Steven Mark Anlage
Imaging The Anisotropic Nonlinear Meissner Effect In Nodal Yba ₂Cu₃O7-Δ Thin-Film Superconductors, Alexander P. Zhuravel, Behnood G. Ghamsari, Cihan Kurter, Philipp Jung, Stephen K. Remillard, John A. Abrahams, Alexander V. Lukashenko, Alexey V. Ustinov, Steven Mark Anlage
Physics Faculty Research & Creative Works
We have directly imaged the anisotropic nonlinear Meissner effect in an unconventional superconductor through the nonlinear electrodynamic response of both (bulk) gap nodes and (surface) Andreev bound states. A superconducting thin film is patterned into a compact self-resonant spiral structure, excited near resonance in the radio-frequency range, and scanned with a focused laser beam perturbation. At low temperatures, direction-dependent nonlinearities in the reactive and resistive properties of the resonator create photoresponse that maps out the directions of nodes, or of bound states associated with these nodes, on the Fermi surface of the superconductor. The method is demonstrated on the nodal …
Depairing Current Density In Cuprate Superconductors, Manlai Liang
Depairing Current Density In Cuprate Superconductors, Manlai Liang
Theses and Dissertations
We report a study of the depairing critical current density in the electron-doped infinite-layer Sr1-xLaxCuO2 and Nd2-xCexCuO4-\delta system. In this work, many new apparatuses were set up to measure the samples. Resistance-versus-temperature transition curves measured at high pulsed current densities show the classic proportionality between the transition-temperature shift and the two-thirds power of the applied current. The measurement provides an assessment of the superfluid density in the system, and a secondary route for obtaining the penetration depth purely through a transport measurements.