| Project/Area Number |
17K05525
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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 II
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| Research Institution | Hokkaido University |
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Principal Investigator |
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| Project Period (FY) |
2017-04-01 – 2021-03-31
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| Project Status |
Completed (Fiscal Year 2020)
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| Budget Amount *help |
¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000)
Fiscal Year 2019: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2018: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2017: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000)
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| Keywords | 強相間電子系 / 奇パリティ多極子 / 低温物性 / 磁性 / 超音波 / アクチノイド / 多極子 / 強磁場 / 極低温 / トロイダル秩序 / 強相関電子系 / 物性実験 / 電気磁気効果 / マルチフェロイクス |
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| Outline of Final Research Achievements |
The elastic response of a uranium compound (UNi4B) exhibiting vortex-like magnetic ordering (magnetic toroidal dipolar ordering), which breaks the spatial inversion symmetry, has been precisely measured by using the ultrasonic phase-comparison method down to very low temperatures and high magnetic fields. We have succeeded in identifying the electric quadrupoles that maintain their degrees of freedom without ordering at the center of a magnetic vortex arrangement in uranium with a honeycomb structure. The response of the quadrupoles depends strongly on the direction of the magnetic field. We discover a new phase V appears at high magnetic fields and low temperatures for H || b. We can conclude that the electric quadrupoles play an important role in the vortex-like magnetic structure of this system, modifying the spin-reorientation process as well.
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| Academic Significance and Societal Importance of the Research Achievements |
磁場下で堅牢な電気四極子自由度を自在に制御できるようになれば、新たな量子メモリや、磁場に対して堅牢な量子デバイスなどへの応用が期待される。今回実証されたのはその基礎となる現象のため，今後はその物理をしっかりと構築することが重要である。また，本研究で採用した強磁場・極低温下における精密超音波測定の手法は様々な化合物に応用可能であり，磁気相図の構築から新奇な量子現象の機構解明に役立てることができる。
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