NIMS Beamline Station at SPring-8

Station Leader

Keisuke Kobayashi

Manager

Hideki Yoshikawa

The concept of WEBRAM (Wide Energy Beamline for Research in Advanced Materials), constructed by NIMS (National Institute for Materials Science, Japan), is "wide energy and bright X-ray". Monochromatic brilliant X-ray from the revolver type undulator can be obtained in the energy region from 2 keV to 20 keV (1st order of double-crystal monochromator) , up to 60keV (3rd order) on samples. It is now possible to carry out the following experiments in nano-material research ; the crystal structure analysis by high angular resolution powder diffraction and the non-destructive depth-profile analysis for the electronic structure by the high-energy X-ray photoemission spectroscopy. Beamline station has participated in the nano-technology network project to support the advanced analysis of frontier nano-materials by brilliant synchrotron radiation X-ray.

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The Beamline Station jointly promotes research and development of SR analysis of advanced materials based on the public use in NIMS and the Innovation-Nanotechnology Network by Advanced Common Facility.

The high-precision powder X-ray diffractometer (photo 1) is installed in the 1st experimental hutch. High brilliance and low dispersion X-rays from the undulator enables high angular resolution X-ray powder diffraction experiments with minimum 2-theta step angle of 0.0005 degrees. The observed FWHM of Si(111) diffraction peaks are usually less than 0.07 degrees. Recently an imaging plate camera system has been developed to be set on the 2-theta arm and has realized high resolution and rapid diffraction pattern observation.

In the 2nd experimental hutch, a photoelectron spectroscopy apparatus is installed (photo 2). The high-energy XPS experiments reduce the surface contamination effect drastically. Especially, it is suitable for analysis of samples which have difficulty in sputter cleaning and non-destructive depth-profile analysis of layered devices. Best energy resolution is 60 meV.

Detection of the valence band in buried Co2MnSi-MgO tunnel junctions by means of photoemission spectroscopy

Applied Physics Letters (2008)

This work reports on the detection of the valence band of buried Heusler compounds by means of hard X-ray photoemission spectroscopy (HXPES). The measurements have been performed on so called "half" tunnel junctions that are thin films of Co2MnSi underneath MgO. The structure of the samples is: MgO(buffer) - Co2MnSi -MgO(tMgO) - AlOx with a thickness tMgO of the upper MgO layer of 2 nm and 20 nm. It is shown that the buried Co2MnSi films covered with 20nm MgO layer exhibit the same valence density of states as in bulk samples.