7,776 research outputs found

    Induced magnetism at the interfaces of a Fe/V superlattice investigated by resonant magnetic x-ray scattering

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    The induced magnetic moments in the V 3d electronic states of interface atomic layers in a Fe(6ML)/V(7ML) superlattice was investigated by x-ray resonant magnetic scattering. The first V atomic layer next to Fe was found to be strongly antiferromagnetically polarized relatively to Fe and the magnetic moments of the next few atomic layers in the interior V region decay exponentially with increasing distance from the interface, while the magnetic moments of the Fe atomic layers largely remain bulk-like. The induced V moments decay more rapidly as observed by x-ray magnetic scattering than in standard x-ray magnetic circular dichroism. The theoretical description of the induced magnetic atomic layer profile in V was found to strongly rely on the interface roughness within the superlattice period. These results provide new insight into interface magnetism by taking advantage of the enhanced depth sensitivity to the magnetic profile over a certain resonant energy bandwidth in the vicinity of the Bragg angles.Comment: 7 pages, 6 figure

    Electronic correlation effects in the Cr2GeC Mn+1AXn phase

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    The magnetic properties, electronic band structure and Fermi surfaces of the hexagonal Cr2GeC system have been studied by means of both generalized gradient approximation (GGA) and the +U corrected method (GGA+U). The effective U value has been computed within the augmented plane-wave theoretical scheme by following the constrained density functional theory formalism of Anisimov et al. [1991 Phys. Rev. B 45, 7570]. On the basis of our GGA+U calculations, a compensated anti-ferromagnetic spin ordering of Cr atoms has been found to be the ground state solution for this material, where a Ge-mediated super-exchange coupling is responsible for an opposite spin distribution between the ABA stacked in-plane Cr-C networks. Structural properties have also been tested and found to be in good agreement with the available experimental data. Topological analysis of Fermi surfaces have been used to qualitatively address the electronic transport properties of Cr2GeC and found an important asymmetrical carrier-type distribution within the hexagonal crystal lattice. We conclude that an appropriate description of the strongly correlated Cr-d electrons is an essential issue for interpreting the material properties of this unusual Cr-based MAX-phase.Comment: 13 pages, 10 picture

    The importance of poverty early in childhood

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    Introduction: Using a poverty line set at 60% of New Zealand’s median national income, nearly one in five New Zealand children (19%) was poor in 2011. This poverty rate is considerably less than that of the United States and Canada, similar to that of Australia, the United Kingdom, Germany and France, and much greater that in Scandinavian countries. These rates are far from immutable; New Zealand’s child poverty rate was much higher in 2004 before social policies were enacted which focused, in part, on the country’s child poverty problem

    Energy Dependence of Cu L2,3 Satellites using Synchrotron Excited X-ray Emission Spectroscopy

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    The L2,3 X-ray emission of Cu metal has been measured using monochromatic synchrotron radiation. The self-absorption effect in the spectra is shown to be very small in our experimental geometry. From the quantitative analysis of spectra recorded at different excitation energies, the L3/L2 emission intensity ratio and the partial Auger-width are extracted. High-energy satellite features on the L3 emission line are separated by a subtraction procedure. The satellite intensity is found to be slowly increasing for excitation energies between the L3, L2 and L1 core-level thresholds due to shake-up and shake-off transitions. As the excitation energy passes the L2 threshold, a step of rapidly increasing satellite intensity of the L3 emission is found due to additional Coster-Kronig processes.Comment: 8 pages, 3 figures, http://link.aps.org/doi/10.1103/PhysRevB.56.1223

    A Checklist of Illinois Centipedes (Chilopoda): Supplement

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    (excerpt) Order SCOLOPENDROMORPHA Family CRYFTOPIDAE Subfamily CRYFTOPINAE Cryptops hyalinus Say 1821. (Fig. 2). B (Cook; Auerbach [1951]), C (Champaign) F (Hardin, Jackson, Johnson, Pope, Saline, Williamson), G (Jackson, Jefferson, Perry, Williamson), H (Clark), I (Randolph, Union), J (Alexander)

    Mindful economy and ecology

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