1999 Fiscal Year Final Research Report Summary
High resoeution, high energy spectroscopy of electronic states on phase transitions
| Project/Area Number |
08405004
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied materials science/Crystal engineering
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| Research Institution | Osaka University |
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Principal Investigator |
SUGA Shigemasa Graduate School of Engineering Osaka University, 基礎工学研究科, 教授 (40107438)
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| Co-Investigator(Kenkyū-buntansha) |
SHIRAI Masafumi Graduate School of Engineering Osaka University, associate Professor, 基礎工学研究科, 助教授 (70221306)
SUZUKI Naoshi Graduate School of Engineering Osaka University, Professor, 基礎工学研究科, 教授 (40029559)
IMADA Shin Graduate School of Engineering Osaka University, assistant Professor, 基礎工学研究科, 講師 (90240837)
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| Project Period (FY) |
1996 – 1999
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| Keywords | Valena Fluctuation / Kondo resonana / bulk sensitive / resonance photoemission / magnetic transition / metal-insulator transition / change ordering |
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| Research Abstract |
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.
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