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1,054 results on '"Kawata, H."'

1. Anomalous electronic correlations in ground state momentum density of Al$_{97}$Li$_3$

Author

Kwiatkowska, J., Barbiellini, B., Kaprzyk, S., Bansil, A., Kawata, H., and Shiotani, N.

Subjects
Condensed Matter - Materials Science, Condensed Matter - Strongly Correlated Electrons
Abstract

We report high resolution Compton scattering measurements on an Al$_{97}$Li$_3$ disordered alloy single crystal for momentum transfer along the [100], [110] and [111] symmetry directions. The results are interpreted via corresponding KKR-CPA (Korringa-Kohn-Rostoker coherent potential approximation) first principles computations. By comparing spectra for Al$_{97}$Li$_3$ and Al, we show that the momentum density in the alloy differs significantly from the predictions of the conventional Fermi liquid picture and that the ground state of Al is modified anomalously by the addition of Li., Comment: 4 pages, 3 figures

Published
2006
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2. A Novel 2D Folding Technique for Enhancing Fermi Surface Signatures in the Momentum Density: Application to Compton Scattering Data from an Al-3at%Li Disordered Alloy

Author

Matsumoto, I., Kwiatkowska, J., Maniawski, F., Itou, M., Kawata, H., Shiotani, N., Kaprzyk, S., Mijnarends, P. E., Barbiellini, B., and Bansil, A.

Subjects
Condensed Matter - Materials Science
Abstract

We present a novel technique for enhancing Fermi surface (FS) signatures in the 2D distribution obtained after the 3D momentum density in a crystal is projected along a specific direction in momentum space. These results are useful for investigating fermiology via high resolution Compton scattering and positron annihilation spectroscopies. We focus on the particular case of the (110) projection in an fcc crystal where the standard approach based on the use of the Lock-Crisp-West (LCW) folding theorem fails to give a clear FS image due to the strong overlap with FS images obtained through projection from higher Brillouin zones. We show how these superposed FS images can be disentangled by using a selected set of reciprocal lattice vectors in the folding process. The applicability of our partial folding scheme is illustrated by considering Compton spectra from an Al-3at%Li disordered alloy single crystal. For this purpose, high resolution Compton profiles along nine directions in the (110) plane were measured. Corresponding highly accurate theoretical profiles in Al-3at%Li were computed within the local density approximation (LDA)-based Korringa-Kohn-Rostoker coherent potential approximation (KKR-CPA) first-principles framework. A good level of overall accord between theory and experiment is obtained, some expected discrepancies reflecting electron correlation effects notwithstanding, and the partial folding scheme is shown to yield a clear FS image in the (110) plane in Al-3%Li., Comment: 24 pages, 8 figures, to appear in Phys. Rev. B

Published
2001
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3. A High-Resolution Compton Scattering Study of the Electron Momentum Density in Al

Author

Ohata, T., Itou, M., Matsumoto, I., Sakurai, Y., Kawata, H., Shiotani, N., Kaprzyk, S., Mijnarends, P. E., and Bansil, A.

Subjects
Condensed Matter - Materials Science
Abstract

We report high-resolution Compton profiles (CP's) of Al along the three principal symmetry directions at a photon energy of 59.38 keV, together with corresponding highly accurate theoretical profiles obtained within the local-density approximation (LDA) based band-theory framework. A good accord between theory and experiment is found with respect to the overall shapes of the CP's, their first and second derivatives, as well as the anisotropies in the CP's defined as differences between pairs of various CP's. There are however discrepancies in that, in comparison to the LDA predictions, the measured profiles are lower at low momenta, show a Fermi cutoff which is broader, and display a tail which is higher at momenta above the Fermi momentum. A number of simple model calculations are carried out in order to gain insight into the nature of the underlying 3D momentum density in Al, and the role of the Fermi surface in inducing fine structure in the CP's. The present results when compared with those on Li show clearly that the size of discrepancies between theoretical and experimental CP's is markedly smaller in Al than in Li. This indicates that, with increasing electron density, the conventional picture of the electron gas becomes more representative of the momentum density and that shortcomings of the LDA framework in describing the electron correlation effects become less important., Comment: 7 pages, 6 figures, regular article

Published
2000
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13. Photoacoustic X-Ray Absorption Near Edge Structure in CuInSe2

Author

Toyoda, T., Masujima, T., Shiwaku, H., Nakanishi, H., Endo, S., Irie, T., Iida, A., Kawata, H., Ando, M., Tamir, Theodor, editor, Lotsch, Helmut K. V., editor, Murphy, John C., editor, Spicer, Jane W. Maclachlan, editor, Aamodt, Leonard C., editor, and Royce, Barrie S. H., editor

Published
1990
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