Showing 1–3 of 3 results for author: Hsu, T C
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Magneto-Optics of type-II superconductors
Authors:
E. Choi,
H. -T. S. Lihn,
H. D. Drew,
T. C. Hsu
Abstract:
The magneto-optical activity of superconducting ${\rm YBa}_{2}{\rm Cu}_{3}{\rm O}_{7}$ observed by Karrai {\it et al.} is not present in many commonly employed models of vortex dynamics. Here we propose a simple, unifying picture for the frequency dependent magneto-optic response of type-II superconductors at low temperatures. We bring together Kohn's theorem, vortex core excitations, and vortex…
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The magneto-optical activity of superconducting ${\rm YBa}_{2}{\rm Cu}_{3}{\rm O}_{7}$ observed by Karrai {\it et al.} is not present in many commonly employed models of vortex dynamics. Here we propose a simple, unifying picture for the frequency dependent magneto-optic response of type-II superconductors at low temperatures. We bring together Kohn's theorem, vortex core excitations, and vortex pinning and damping into a single expression for the conductivity tensor. The theory describes magneto-optical activity observed in infrared transmission measurements of thin films of ${\rm YBa}_{2}{\rm Cu}_{3}{\rm O}_{7}$.
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Submitted 13 October, 1993;
originally announced October 1993.
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Level repulsion in integrable and almost-integrable quantum spin models
Authors:
Theodore C. Hsu,
J. C. Angles d'Auriac
Abstract:
The repartition of the separation between energy levels of various isotropic S=1/2 antiferromagnetic chains is studied numerically with the aim of investigating the transition from integrable to non-integrable systems. We begin by displaying the level separation distribution of the integrable Bethe chain. Then two non-integrable systems, two coupled chains and a next-nearest-neighbor coupled cha…
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The repartition of the separation between energy levels of various isotropic S=1/2 antiferromagnetic chains is studied numerically with the aim of investigating the transition from integrable to non-integrable systems. We begin by displaying the level separation distribution of the integrable Bethe chain. Then two non-integrable systems, two coupled chains and a next-nearest-neighbor coupled chain, are studied as a function of the coupling. We examine how the level spacing evolves from the Poisson distribution to the GOE distribution. Finally we consider the Haldane-Shastry $1/r^{2}$ model. A number of conclusions regarding the behaviour and relevance of the level spacing distribution in these spin systems is drawn.
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Submitted 3 November, 1992;
originally announced November 1992.
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Absence of Dipole Transitions in Vortices of Type II Superconductors
Authors:
Theodore C. Hsu
Abstract:
The response of a single vortex to a time dependent field is examined microscopically and an equation of motion for vortex motion at non-zero frequencies is derived. Of interest are frequencies near $Δ^{2}/E_{F}$, where $Δ$ is the bulk energy gap and $E_{F}$ is the fermi energy. The low temperature, clean, extreme type II limit and maintaining of equilibrium with the lattice are assumed. A simpl…
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The response of a single vortex to a time dependent field is examined microscopically and an equation of motion for vortex motion at non-zero frequencies is derived. Of interest are frequencies near $Δ^{2}/E_{F}$, where $Δ$ is the bulk energy gap and $E_{F}$ is the fermi energy. The low temperature, clean, extreme type II limit and maintaining of equilibrium with the lattice are assumed. A simplification occurs for large planar mass anisotropy. Thus the results may be pertinent to materials such as $NbSe_2$ and high temperature superconductors. The expected dipole transition between core states is hidden because of the self consistent nature of the vortex potential. Instead the vortex itself moves and has a resonance at the frequency of the transition.
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Submitted 30 April, 1992;
originally announced April 1992.