Success in Measuring True Electric Band Structure of Solids (Press Release)
- Release Date
- 19 Aug, 2011
- BL15XU (WEBRAM)
National Institute for Materials Science (NIMS)
A research group led by Shigenori Ueda (Researcher) and his colleagues at the NIMS Beamline Station at SPring-8 (Station Leader, Osami Sakata), part of the Research Network and Facility Services Division of NIMS (President, Sukekatsu Ushioda), has succeeded in measuring the true band dispersion of solids by angle-resolved photoemission spectroscopy (ARPES) in the hard X-ray region for the first time in the world. This was realized using SPring-8 equipment for performing hard X-ray photoemission spectroscopy, which enables the measurement of the electron state inside a solid with the highest resolution in the world, and a theoretical method called first-principles calculation. The systems targeted were tungsten (W), a typical metal, and gallium arsenide (GaAs), a typical semiconductor. This research was jointly carried out with the University of California Davis, Lawrence Berkeley National Laboratory, Universität Erlangen-Nürnberg, Johannes Gutenberg-Universität Mainz, Research Center Jülich, and Ludwig Maximillian University. The achievement of this study is expected to enable the electronic band structure of various functional materials to be measured and provide a means of creating new functional materials. The results were published online in Nature Materials, published by the Nature Publishing Group, on 15 August 2011. Publication: |
<<Figures>>
(a) Result of hard X-ray ARPES measurement at room temperature (300 K). No band dispersion is observed when the Debye-Waller factor (W) is small (0.09).
(b) Result of hard X-ray ARPES measurement at low temperature (30 K). Band dispersion is observed when W=0.45.
(c) Comparison between the results obtained by removing background from (b) and theoretical calculation (green).
(d) Result of theoretical calculation considering the excitation probability of photoelectrons. Band dispersion, which is not observed at room temperature, is clearly observed at 30 K. The experimental result is in good qualitative agreement with the theoretical result.
(a) Result of hard X-ray ARPES measurement at room temperature (300 K). No band dispersion is observed when W is small (0.01).
(b) Result of hard X-ray ARPES measurement at low temperature (30 K). Band dispersion is observed when W=0.31.
(c) Comparison between the results obtained by removing background from (b) and theoretical calculation (green).
(d) Result of theoretical calculation considering the excitation probability of photoelectrons. Band dispersion, which is not observed at room temperature, is clearly observed at 30 K, similarly to W. The experimental result is in good qualitative agreement with the theoretical result.
For more information, please contact: Dr. Keisuke Kobayashi (NIMS) |
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