Papers by Keyword: Inelastic Neutron Scattering

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Authors: Kentaro Sato, Masato Matsuura, Masanori Enoki, Kazuyoshi Yamada, Masaki Fujita
Abstract: We have performed inelastic neutron scattering measurement on high-transition temperature superconductor La1.90Sr0.10CuO4 with utilizing a Fermi chopper spectrometer. We succeeded in converting the observed neutron scattering intensity into a dynamical structure factor in the absolute unit by attempting two methods with analyzing (i) incoherent scattering intensity from the sample itself and (ii) that from vanadium standard. The total squared moment <M2> was evaluated to be 0.176 μB2/Cu, which is much smaller than the value for the parent compound, indicating a markedly change of electronic state by hole-doping.
291
Authors: E. Kentzinger, Veronique Pierron-Bohnes, M.C. Cadeville, Winfried Petry, B. Hennion
365
Authors: S. Danilkin, A. Beskrovni, E. Jadrowski
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Authors: Dieter Strauch, B. Dorner, A.A. Ivanov, M. Krisch, J. Serrano, Alexey Bosak, Wolfgang J. Choyke, B. Stojetz, Michael Malorny
Abstract: Preliminary results for the phonon dispersion curves of hexagonal 4H-SiC from experimental inelastic neutron (INS) and X-ray scattering (IXS) are reported and contrasted with those of cubic 3C-SiC and silicon. The experimental frequencies and scattering intensities are in excellent agreement with those from first-principles calculations using density-functional methods. The relative merits of the two experimental techniques and aspects of the density functional perturbation theory and the so-called frozen phonon method for the determination of the basic phonon properties are briefly outlined.
689
Authors: Daniele Colognesi, Antonino Pietropaolo, Aníbal Javier Ramírez-Cuesta, Michele Catti, Angelo Claudio Nale, Marco Zoppi
Abstract: Lithium imide (Li2NH) and amide (LiNH2) belong to the Li-H-N system, which has been recently considered for on-board hydrogen storage applications. However the imide low-temperature crystal structure is still highly controversial, with at least six options compatible with the diffraction experimental findings. A complementary study on low-temperature Li2NH and LiNH2 has been recently accomplished by the authors using neutron spectroscopy (with energy transfer in the 3-500 meV range). The rationale of these measurements was that crystal structures (especially their proton arrangements) affect in a strong way the neutron scattering spectra, so that a combined use of computer ab-initio simulations and inelastic neutron scattering could be a stringent validation method for the various models. Data analysis has pointed out broad and almost featureless proton-projected phonon densities of states for lithium imide, with large differences in the data sets derived from forward scattering and backscattering detector banks. On the contrary, a sharp phonon spectrum and much less discrepancy was found applying the same analytic procedure to lithium amide. This Li2NH peculiarity has been interpreted as an effect of the fast proton jump diffusion among the available lattice sites, which smears out the phonon vibrational excitations in a momentum transfer-dependent way.
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