| Project/Area Number |
16K05409
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Condensed matter physics I
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| Research Institution | Rikkyo University |
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Principal Investigator |
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| Project Period (FY) |
2016-04-01 – 2019-03-31
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| Project Status |
Completed (Fiscal Year 2018)
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| Budget Amount *help |
¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000)
Fiscal Year 2018: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2017: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2016: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
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| Keywords | バナジウム酸化物 / 薄膜 / 電子状態 / 金属絶縁体転移 / 光電子分光 / 全反射高速陽電子回折 / 強相関 / X線吸収分光 / 超薄膜 / 表面・界面物性 / 物性実験 |
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| Outline of Final Research Achievements |
The aim of this study is to synthesize a thin film of a VO crystal, whose physical properties have not been cleared because the crystal is hard to synthesize in an atmospheric condition, on an Ag(100) substrate that has a lattice well commensurate with VO(100). It was found that a V oxide film with a (1×1) periodicity with respect to Ag(100) can be formed by a reactive deposition method. The film was identified as the VO(100) film with a NaCl-type crystal structure from the analyses of photoemission spectroscopy (PES), X-ray absorption spectroscopy and total-reflection high-energy positron diffraction results. The electronic structure of the VO film was investigated by high-resolution PES, and it was found that the electronic structure of the film was metallic at temperatures higher than 4.86 K. The results indicates that the metal-insulator transition does not occur in the VO film, unlike the case for the other V oxides.
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| Academic Significance and Societal Importance of the Research Achievements |
3d遷移金属酸化物は、構造が単純な強相関系として注目を集めてきた。これまでTiOは金属、MnO、FeO等は反強磁性絶縁体であることは判明していたが、その中間にあるVOの電子状態は不明であった。理論的にも、これが金属か絶縁体かは意見が別れていた。本研究ではVOは金属であることが明らかになり、これはVOをめぐる長年の論争に終止符を打つものである。また、バナジウム酸化物はそのMITの起源をめぐって膨大な研究が行われてきたが、VOのみはMITの有無すら不明であった。今回VOはMITを起こさないことが明らかとなった。以上は、物性物理学における長年のミッシング・リンクをつなぐ成果と言える。
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