3,606 research outputs found

    Ab-initio Prediction of Conduction Band Spin Splitting in Zincblende Semiconductors

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    We use a recently developed self-consistent GWGW approximation to present systematic \emph{ab initio} calculations of the conduction band spin splitting in III-V and II-V zincblende semiconductors. The spin orbit interaction is taken into account as a perturbation to the scalar relativistic hamiltonian. These are the first calculations of conduction band spin splittings based on a quasiparticle approach; and because the self-consistent GWGW scheme accurately reproduces the relevant band parameters, it is expected to be a reliable predictor of spin splittings. The results are compared to the few available experimental data and a previous calculation based on a model one-particle potential. We also briefly address the widely used {\bf k}â‹…\cdot{\bf p} parameterization in the context of these results.Comment: 9 pages, 1 figur

    Anticardiolipin Antibodies Recognize β(2)-Glycoprotein I Structure Altered by Interacting with an Oxygen Modified Solid Phase Surface

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    Anticardiolipin antibodies (aCL) derived from the sera of individuals exhibiting the antiphospholipid syndrome (APS) directly bind to beta(2)-glycoprotein I (beta(2)-GPI), which is adsorbed to an oxidized polystyrene surface. Oxygen atoms were introduced on a polystyrene surface by irradiation with electron or gamma-ray radiation. X-ray photoelectron spectroscopy revealed the irradiated surfaces were oxidized to generate C-O and C=O moieties. aCL derived from either APS patients or (NZW x BXSB)F-1 mice bound to beta(2)-GPI coated on the irradiated plates, depending on the radiation dose. Antibody binding to beta(2)-GPI on the irradiated plates was competitively inhibited by simultaneous addition of cardiolipin (CL)-coated latex beads mixed together with beta(2)-GPI but were unaffected by addition of excess beta(2)-GPI, CL micelles, or CL-coated latex beads alone. There was a high correlation between binding values of aCL in sera from 40 APS patients obtained by the anti-beta(2)-GPI enzyme-linked immunosorbent assay (ELISA) using the irradiated plates and those by the beta(2)-GPI-dependent aCL ELISA. Therefore, aCL have specificity for an epitope on beta(2)-GPI. This epitope is expressed by a conformational change occurring when beta(2)-GPI interacts with an oxygen-substituted solid phase surface

    Maxwell stress in fluid mixtures

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    We examine the structure of Maxwell stress in binary fluid mixtures under an external electric field and discuss its consequence. In particular, we show that, in immiscible blends, it is intimately related to the statistics of domain structure. This leads to a compact formula, which may be useful in the investigation of electro-rheological effects in such systems. The stress tensor calculated in a phase separated fluid under a steady electric field is in a good agreement with recent experiments.Comment: 5 page

    Dynamics of a Generalized Cosmological Scalar-Tensor Theory

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    A generalized scalar-tensor theory is investigated whose cosmological term depends on both a scalar field and its time derivative. A correspondence with solutions of five-dimensional Space-Time-Matter theory is noted. Analytic solutions are found for the scale factor, scalar field and cosmological term. Models with free parameters of order unity are consistent with recent observational data and could be relevant to both the dark-matter and cosmological-"constant" problems.Comment: 13 page

    Alternative formalism to the slave particle mean field theory of the t-J model without deconfinement

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    An alternative formalism that does not require the assumption of the deconfinement phase of a U(1) gauge field is proposed for the slave particle mean field theory. Starting form the spin-fermion model, a spinon field, which is either fermion or boson, is introduced to represent the localized spin moment. We find a d-wave superconductive state in the mean field theory in the case of the fermion representation of the localized spin moment that corresponds to the slave boson mean field theory of the t-J model, whereas the d-wave superconductive state is absent in case of the Schwinger boson representation of the localized spin moments.Comment: 8 page

    Ultrafast Dynamics of Vibrational Symmetry Breaking in a Charge-ordered Nickelate

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    The ability to probe symmetry breaking transitions on their natural time scales is one of the key challenges in nonequilibrium physics. Stripe ordering represents an intriguing type of broken symmetry, where complex interactions result in atomic-scale lines of charge and spin density. Although phonon anomalies and periodic distortions attest the importance of electron-phonon coupling in the formation of stripe phases, a direct time-domain view of vibrational symmetry breaking is lacking. We report experiments that track the transient multi-THz response of the model stripe compound La1.75_{1.75}Sr0.25_{0.25}NiO4_{4}, yielding novel insight into its electronic and structural dynamics following an ultrafast optical quench. We find that although electronic carriers are immediately delocalized, the crystal symmetry remains initially frozen - as witnessed by time-delayed suppression of zone-folded Ni-O bending modes acting as a fingerprint of lattice symmetry. Longitudinal and transverse vibrations react with different speeds, indicating a strong directionality and an important role of polar interactions. The hidden complexity of electronic and structural coupling during stripe melting and formation, captured here within a single terahertz spectrum, opens new paths to understanding symmetry breaking dynamics in solids.Comment: 21 pages, 4 figures; updated version with journal re

    Snow accumulation by entering low-pressures from the coast to Dome Fuji, East Antarctica

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    The Tenth Symposium on Polar Science/Ordinary sessions: [OM] Polar Meteorology and Glaciology, Wed. 4 Dec. / 2F Auditorium, National Institute of Polar Researc

    Half-skyrmion picture of single hole doped CuO_2 plane

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    Based on the Zhang-Rice singlet picture, it is argued that the half-skyrmion is created by the doped hole in the single hole doped high-T_c cuprates with N'eel ordering. The spin configuration around the Zhang-Rice singlet, which has the form of superposition of the two different d-orbital hole spin states, is studied within the non-linear \sigma model and the CP^1 model. The spin configurations associated with each hole spin state are obtained, and we find that the superposition of these spin configuration turns out to be the half-skyrmion that is characterized by a half of the topological charge. The excitation spectrum of the half-skyrmion is obtained by making use of Lorentz invariance of the effective theory and is qualitatively in good agreement with angle resolved photoemission spectroscopy on the parent compunds. Estimated values of the parameters contained in the excitation spectrum are in good agreement with experimentally obtained values. The half-skyrmion theory suggests a picture for the difference between the hole doped compounds and the electron doped compounds.Comment: 13 pages, 2 figures, to be published in Phys. Rev.
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