2003 Fiscal Year Final Research Report Summary
Research on partial electronic density of states in superoonducting diborides by x-ray absorption and emission spectroscopies
| Project/Area Number |
14540330
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
固体物性Ⅱ(磁性・金属・低温)
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| Research Institution | The University of Electro-Communications |
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Principal Investigator |
YAMADA Nobyoshi The University of Electro-Communications, Faculty of Electro-Communications, Professor, 電気通信学部, 教授 (40017405)
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| Co-Investigator(Kenkyū-buntansha) |
OGUCHI Tamio Hiroshima University, Graduate School of Advanced Sciences of Matter, Professor, 大学院・先端物質科学研究科, 教授 (90253054)
KUROKI Kazuhiko The University of Electro-Communications, Faculty of Electro-Communications, Associate Professor, 電気通信学部, 助教授 (10242091)
WATANABE Masamitsu RIKEN, Harima Institute at Spring-8, Reseacher, 播磨研究所, 研究員 (00300674)
NAKAMURA Jin The University of Electro-Communications, Faculty of Electro-Communications, Research Associate, 電気通信学部, 助手 (50313416)
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| Project Period (FY) |
2002 – 2003
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| Keywords | Super Conductivity / MgB2 / Synchrotron Radiation / x-ray Absorption Spectroscopy / x-ray Emission Spectroscopy |
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| Research Abstract |
X-ray emission (XES) and obsorption (XAS) spectra near the B K-edge were measured on single-crystalline AlB2 which is an isostructural diboride of superconducting MgB2, and on single-crystalline MgB2. The partial density of states (PDOS) of B-2p-σ and p-π orbitals were derived from the polarization dependence of XES and XAS spectra.
The overall features of PDOS were found to be in good agreement with the result of band calculation of AlB2 and MgB2. There are considerable amounts of PDOS near the Fermi energy in AlB2 similarly to that in MgB2, but there are almost no PDOS in p-σ orbitals of AlB2 near the Fermi energy, i.e., a pseudo-gap in p-σ state and a broad metallic state in p-π state are observed, On the contrary, there are considerable amount of PDOS in p-σ orbitals of MgB2 near the Fermi energy, i.e., broad metallic states in p-π state and p-σ state are observed
The present result indirectly supports scenarios that the p-σ holes play an important role in the occurrence of superconductivity in MgB2.
The effect of electron correlation (EC) on the partial density of state (PDOS) were studied by the polarization dependence of x-ray emission and absorption spectra of MgB2, AlB2 single crystals.
There are some discrepancies between the observed PDOSs and theoretical ones, although these are contrary to the electron-correlation effects. The present results suggest that the EC effect is less than the experimental error (0.2 eV), which indirectly supports a scenario that electron-phonon interaction plays an essential role in the occurrence of superconductivity.
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