Spin-roton excitations in the cuprate superconductors

We identify a new kind of elementary excitations, spin-rotons, in the doped Mott insulator. They play a central role in deciding the superconducting transition temperature Tc, resulting in a simple Tc formula,Tc=Eg/6, with Eg as the characteristic energy scale of the spin rotons. We show that the degenerate S=1 and S=0 rotons can be probed by neutron scattering and Raman scattering measurements, respectively, in good agreement with the magnetic resonancelike mode and the Raman A1g mode observed in the high-Tc cuprates.Comment: 10 pages, 9 figure

The Fermi level effect in III-V intermixing: The final nail in the coffin?

Copyright 1997 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. This article appeared in Journal of Applied Physics 81, 2179 (1997) and may be found at

Simple one-dimensional quantum-mechanical model for a particle attached to a surface

We present a simple one-dimensional quantum-mechanical model for a particle attached to a surface. We solve the Schr\"odinger equation in terms of Weber functions and discuss the behavior of the eigenvalues and eigenfunctions. We derive the virial theorem and other exact relationships as well as the asymptotic behaviour of the eigenvalues. We calculate the zero-point energy for model parameters corresponding to H adsorbed on Pd(100) and also outline the application of the Rayleigh-Ritz variational method

Triaxially deformed relativistic point-coupling model for Λ\Lambda hypernuclei: a quantitative analysis of hyperon impurity effect on nuclear collective properties

The impurity effect of hyperon on atomic nuclei has received a renewed interest in nuclear physics since the first experimental observation of appreciable reduction of $E2$ transition strength in low-lying states of hypernucleus $^{7}_\Lambda$Li. Many more data on low-lying states of $\Lambda$ hypernuclei will be measured soon for $sd$-shell nuclei, providing good opportunities to study the $\Lambda$ impurity effect on nuclear low-energy excitations. We carry out a quantitative analysis of $\Lambda$ hyperon impurity effect on the low-lying states of $sd$-shell nuclei at the beyond-mean-field level based on a relativistic point-coupling energy density functional (EDF), considering that the $\Lambda$ hyperon is injected into the lowest positive-parity ($\Lambda_s$) and negative-parity ($\Lambda_p$) states. We adopt a triaxially deformed relativistic mean-field (RMF) approach for hypernuclei and calculate the $\Lambda$ binding energies of hypernuclei as well as the potential energy surfaces (PESs) in $(\beta, \gamma)$ deformation plane. We also calculate the PESs for the $\Lambda$ hypernuclei with good quantum numbers using a microscopic particle rotor model (PRM) with the same relativistic EDF. The triaxially deformed RMF approach is further applied in order to determine the parameters of a five-dimensional collective Hamiltonian (5DCH) for the collective excitations of triaxially deformed core nuclei. Taking $^{25,27}_{\Lambda}$Mg and $^{31}_{\Lambda}$Si as examples, we analyse the impurity effects of $\Lambda_s$ and $\Lambda_p$ on the low-lying states of the core nuclei...Comment: 15 pages with 18 figures and 1 table (version to be published in Physical Review C

Hybrid exciton-polaritons in a bad microcavity containing the organic and inorganic quantum wells

We study the hybrid exciton-polaritons in a bad microcavity containing the organic and inorganic quantum wells. The corresponding polariton states are given. The analytical solution and the numerical result of the stationary spectrum for the cavity field are finishedComment: 3 pages, 1 figure. appear in Communications in Theoretical Physic

The ACS Virgo Cluster Survey. XVII. The Spatial Alignment of Globular Cluster Systems With Early-Type Host Galaxies

We study the azimuthal distribution of globular clusters (GCs) in early-type galaxies and compare them to their host galaxies using data from the ACS Virgo Cluster Survey. We find that in host galaxies with visible elongation (epsilon > 0.2) and intermediate to high luminosities (M_z<-19), the GCs are preferentially aligned along the major axis of the stellar light. The red (metal-rich) GC subpopulations show strong alignment with the major axis of the host galaxy, which supports the notion that these GCs are associated with metal-rich field stars. The metal-rich GCs in lenticular galaxies show signs of being more strongly associated with disks rather than bulges. Surprisingly, we find that the blue (metal-poor) GCs can also show the same correlation. If the metal-poor GCs are part of the early formation of the halo and built up through mergers, then our results support a picture where halo formation and merging occur anisotropically, and where the present day major axis is an indicator of the preferred merging axis.Comment: 8 pages, 7 figures, accepted for publication in The Astrophysical Journa

Frozen water waves over rough topographical bottoms

The propagation of surface water waves over rough topographical bottoms is investigated by the multiple scattering theory. It is shown that the waves can be localized spatially through the process of multiple scattering and wave interference, a peculiar wave phenomenon which has been previously discussed for frozen light in optical systems (S. John, Nature {\bf 390}, 661, (1997)). We demonstrate that when frozen, the transmission of the waves falls off exponentially, and a cooperative behavior appears, fully supporting previous predictions. A phase diagram method is used to illustrate this distinct phase states in the wave propagation.Comment: 4 pages and 5 figure

On Size and Shape of the Average Meson Fields in the Semibosonized Nambu & Jona-Lasinio Model

We consider a two-flavor Nambu \& Jona-Lasinio model in Hartree approximation involving scalar-isoscalar and pseudoscalar-isovector quark-quark interactions. Average meson fields are defined by minimizing the effective Euklidean action. The fermionic part of the action, which contains the full Dirac sea, is regularized within Schwinger's proper-time scheme. The meson fields are restricted to the chiral circle and to hedgehog configurations. The only parameter of the model is the constituent quark mass $M$ which simultaneously controls the regularization. We evaluate meson and quark fields self-consistently in dependence on the constituent quark mass. It is shown that the self-consistent fields do practically not depend on the constituent quark mass. This allows us to define a properly parameterized reference field which for physically relevant constituent masses can be used as a good approximation to the exactly calculated one. The reference field is chosen to have correct behaviour for small and large radii. To test the agreement between self-consistent and reference fields we calculate several observables like nucleon energy, mean square radius, axial-vector constant and delta-nucleon mass splitting in dependence on the constituent quark mass. The agreement is found to be very well. Figures available on request.Comment: 12 pages (LATEX), 3 figures available on request, report FZR 93-1

Moisture absorption characteristics and mechanical degradation of composite lattice truss core sandwich panel in a hygrothermal environment

This paper investigates the impact of hygrothermal aging upon the compressive mechanical properties of carbon fiber reinforced plastics (CFRP) composite sandwich panels with a tetrahedral truss core. Gravimetric absorption data, through accelerated moisture absorption tests, were presented for three different temperatures of 30 °C, 55 °C and 80 °C. Predictions by Fickian and Langmuir-type diffusion models were compared to evaluate which one best describe the moisture diffusion process in the sandwich panels. A subroutine implementing the Langmuir-type diffusion model in ABAQUS was developed to simulate the variations of moisture concentration. The compressive properties of composite strut and tetrahedral truss cores sandwich panel after hygrothermal aging at different temperatures were tested, respectively. The experimental results indicated that the degradation of compressive properties of composite sandwich panel was induced by the combined effect of temperature and moisture absorption. Analytical expressions were developed to predict the compressive strength and stiffness of the sandwich panel following hygrothermal aging. A good agreement was found between the predictions by finite element, analytical model and experimental results

Gravity waves over topographical bottoms: Comparison with the experiment

In this paper, the propagation of water surface waves over one-dimensional periodic and random bottoms is investigated by the transfer matrix method. For the periodic bottoms, the band structure is calculated, and the results are compared to the transmission results. When the bottoms are randomized, the Anderson localization phenomenon is observed. The theory has been applied to an existing experiment (Belzons, et al., J. Fluid Mech. {\bf 186}, 530 (1988)). In general, the results are compared favorably with the experimental observation.Comment: 15 pages, 7 figure