| Project/Area Number |
18K18728
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| Research Category |
Grant-in-Aid for Challenging Research (Exploratory)
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| Allocation Type | Multi-year Fund |
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| Review Section |
Medium-sized Section 13:Condensed matter physics and related fields
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| Research Institution | The University of Tokyo |
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Principal Investigator |
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| Project Period (FY) |
2018-06-29 – 2020-03-31
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| Project Status |
Completed (Fiscal Year 2019)
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| Budget Amount *help |
¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000)
Fiscal Year 2019: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
Fiscal Year 2018: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000)
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| Keywords | 強磁場 / 分子軌道 / 金属絶縁体転移 / 絶縁体金属転移 / モット絶縁体 / 化学的カタストロフィー / 超強磁場 |
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| Outline of Final Research Achievements |
Dimerization of two atoms in solids is a phenomenon that has been observed several materials and localization of electrons due to it sometimes induces metal-insulator transition. A molecular orbital is formed when the dimerization takes place, and thus the dimers can be regarded as molecules in solids. VO2 is a prototypical such dimer crystal and the magnetic-field-induced insulator-metal transition is expected to occur if the collapse of the molecular orbital is induced by controlling electron spins. In the present study, we utilize controlling stability of the molecular orbital formation by doping of W and have investigated the possible chemical catastrophe (CC) mechanism. As the result, we have successfully found the field-induced insulator-metal transition in the W-doped VO2 with 6% of W at approximately 500 T. It is a concrete evidence of occurrence of the CC in solids.
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| Academic Significance and Societal Importance of the Research Achievements |
純粋な分子の化学的カタストロフィー現象には10万テスラ以上の磁場が必要であり、宇宙物理において主に理論的に研究されている。また、計算機科学の発展によって、そのような宇宙強磁場では新しい分子軌道形態も理論的に発見されている。今回、固体内において類似の現象が実験的に発見されたことで、分子や原子の電子状態への極限強磁場効果について、宇宙物理との学際的研究が展開可能でり学術的意義は大きい。さらに、固体物理的見地からは、半世紀以上にわたり不明であった絶縁体金属転移機構への電子スピンの役割が、直接的に実験から解明されたインパクトは大きい。
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