High resoeution, high energy spectroscopy of electronic states on phase transitions

Changes of electronic states near the Fermi level on phase transitions are extensivelu studied by means of high resolution spectroscopy。The resonance photoemission technique was intensively employed.In the former half of the research，the spectral changes of the low carrier heavy fermion system Yb I D24个D 2 As I D 23个D 2 and related compounds were studied.The high reslution photoemission was successfully performed in the Kondo insulator system YbB I D212个D2.In the case of the Nd I D21-x I D 2 Sr I D 2 x ii D 2 MnO I D 23 ii D 2，spectral changes through paramagnetic insulator-ferromagnetic metal-charge ordered insulator were observed for x=0.5.For x=0.47，paramagnetic insulator-ferromagnetic metal transition was observed and the Fermi cut off was observed down to the lowest temperature.In the latter half of the research，we constructed and commissioned the world-best performance soft X-ray beam line at SPring-8。The photoemission performed at 900 eV for Yb system has shown that the surface Yb I D12+文件D1is almost suppressed。Thus the deconvolution which has been always required to derive the bulk Yb I D12+ii D1 components from the spectra measured near 100 eV is no more necessary to know the genuine bulk electronic states.The situation was more severe for the Ce system，where the deconvolution was useless because of the overlap of surface and bulk components。However，our bulk sensitive photoemision technique is found to provide the bulk spectrum。Thus we have found that the Ce4f spectra can be scaled by the Kondo temperature.This unprecedented results are published in Nature and stimulating many scientists in the world.In parallel，the structure and magnetism were theoretically studied for taransition metal nitrides and YCoB systems。The lattice constants in the nonmagnetic phase，total energy，as well as magnetic moments were calculated.

Changes of electronic states near the Fermi level on phase transitions are extensivelu studied by means of high resolution spectroscopy. The resonance photoemission technique was intensively employed. In the former half of the research, the spectral changes of the low carrier heavy fermion system YbィイD24ィエD2AsィイD23ィエD2 and related compounds were studied. The high reslution photoemission was successfully performed in the Kondo insulator system YbBィイD212ィエD2. In the case of the NdィイD21-xィエD2SrィイD2xィエD2MnOィイD23ィエD2, spectral changes through paramagnetic insulator-ferromagnetic metal-charge ordered insulator were observed for x=0.5. For x=0.47, paramagnetic insulator-ferromagnetic metal transition was observed and the Fermi cut off was observed down to the lowest temperature.In the latter half of the research, we constructed and commissioned the world-best performance soft X-ray beam line at SPring-8. The photoemission performed at 900eV for Yb system has shown that the surface YbィイD12+ィエD1 is almost suppressed. Thus the deconvolution which has been always required to derive the bulk YbィイD12+ィエD1 components from the spectra measured near 100eV is no more necessary to know the genuine bulk electronic states.The situation was more severe for the Ce system, where the deconvolution was useless because of the overlap of surface and bulk components. However, our bulk sensitive photoemision technique is found to provide the bulk spectrum. Thus we have found that the Ce 4f spectra can be scaled by the Kondo temperature. This unprecedented results are published in Nature and stimulating many scientists in the world.In parallel, the structure and magnetism were theoretically studied for taransition metal nitrides and YCoB systems. The lattice constants in the nonmagnetic phase, total energy, as well as magnetic moments were calculated.