| Project/Area Number |
20H02605
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Review Section |
Basic Section 29010:Applied physical properties-related
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| Research Institution | Kyoto University |
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Principal Investigator |
Miyauchi Yuhei 京都大学, エネルギー理工学研究所, 教授 (10451791)
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| Co-Investigator(Kenkyū-buntansha) |
宮田 耕充 東京都立大学, 理学研究科, 准教授 (80547555)
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| Project Period (FY) |
2020-04-01 – 2023-03-31
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| Project Status |
Completed (Fiscal Year 2022)
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| Budget Amount *help |
¥17,680,000 (Direct Cost: ¥13,600,000、Indirect Cost: ¥4,080,000)
Fiscal Year 2022: ¥5,460,000 (Direct Cost: ¥4,200,000、Indirect Cost: ¥1,260,000)
Fiscal Year 2021: ¥5,460,000 (Direct Cost: ¥4,200,000、Indirect Cost: ¥1,260,000)
Fiscal Year 2020: ¥6,760,000 (Direct Cost: ¥5,200,000、Indirect Cost: ¥1,560,000)
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| Keywords | ワイル半金属 / 赤外光電流 / 赤外光起電力 / 量子物質 / 赤外光電変換 / 赤外 / ワイル / 光電変換 |
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| Outline of Research at the Start |
本研究では、従来の半導体pn接合では原理的に難しかった室温で高効率動作が可能な革新的赤外光電変換素子の実現を目指す。具体的には、赤外光領域において室温での巨大なバルク光起電力効果の発現が予想されているカルコゲナイド系層状ワイル（Weyl）半金属の赤外光学応答を明らかにし、非従来型の高効率赤外光電変換学理と最適な試料・素子構造を見出す。
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| Outline of Final Research Achievements |
Weyl semimetal crystals TaIrTe4 and Co3Sn2S2 were synthesized for various experiments. Using TaIrTe4, devices were fabricated for polarization-resolved spatial mapping of photocurrent under infrared light (4 μm wavelength) irradiation and for measuring its dependence on the irradiation light frequency. As a result, it was found that the contributions of thermoelectric effect inside the material and nonlinear optical response near the surface could be separately captured by the frequency dependent measurements; the latter can be interpreted as originating from the topological effect. For Co3Sn2S2, the phonon modes and frequencies were identified via polarization-resolved Raman scattering measurements, and Fano effect due to the electron Raman scattering contribution was revealed. In addition, methods for synthesis of large-area atomic wires such as WTe and their conversion to ribbon-like large-area networks such as Weyl semimetal WTe2 were developed.
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| Academic Significance and Societal Importance of the Research Achievements |
TaIrTe4における赤外光電流の起源を切り分けて捉えられることを示した成果は、非従来型赤外光電変換機構の解明に向けた重要な手がかりを与えるものである。単結晶Co3Sn2S2のラマン散乱スペクトル構造とその起源を明らかにした成果は、結晶の簡易構造同定や、フェルミエネルギー近傍の低エネルギー電子状態プローブとしてのラマン分光の可能性を示したもので、今後赤外光応答を含む各種物性研究の発展に寄与すると期待される。また、本研究で開発したWTe等原子細線の大面積合成と、そのWTe2等のリボン状大面積ネットワークへの転換技術は、今後のカルコゲナイド系試料を利用した大面積素子作製の基盤となる成果である。
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