| Project/Area Number |
17K14328
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| Research Category |
Grant-in-Aid for Young Scientists (B)
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| Allocation Type | Multi-year Fund |
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| Research Field |
Condensed matter physics II
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| Research Institution | Tohoku University |
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Principal Investigator |
Shimizu Yusei 東北大学, 金属材料研究所, 助教 (90751115)
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| Project Period (FY) |
2017-04-01 – 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: ¥260,000 (Direct Cost: ¥200,000、Indirect Cost: ¥60,000)
Fiscal Year 2018: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2017: ¥2,990,000 (Direct Cost: ¥2,300,000、Indirect Cost: ¥690,000)
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| Keywords | ウラン化合物 / 非従来型超伝導 / 超伝導対称性 / 磁気応答 / 純良単結晶 / 強磁場物性 / アクチノイド化合物 / 強相関電子系 |
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| Outline of Final Research Achievements |
In the present work, we studied the superconducting symmetry, magnetic response, non-fermi-liquid behavior, and high-field properties of exotic uranium superconductors. The quasiparticle excitations in the unconventional superconducting state of (U,Th)Be13 and its magnetic response have been studied using single-crystalline samples, and it has been revealed that the second transition is owing to the change in the superconducting order parameter. The superconducting symmetry of UBe13 has also been investigated using the temperature variation of upper critical field Hc2 under high pressures. It has been shown that the pressure and temperature dependence of the Hc2 in UBe13 is successfully explained by the spin-triplet superconductivity. Moreover, the physical properties of heavy-fermion superconductors UPd2Al3 and UNi2Al3 have also been investigated using single-crystalline samples. The metamagnetic transition has been observed for the first time in UNiAl3 (at 78 T) and U(Pd,Ni)2Al3.
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| Academic Significance and Societal Importance of the Research Achievements |
アクチノイド化合物は、5f電子が遍歴性と局在性の両面的な性質を持ち、強いスピン軌道相互作用を持つことによって、非従来型超伝導のみならず、多極子秩序、非フェルミ液体、トポロジカル絶縁体など、多岐にわたる異常な量子現象をもたらす。アクチノイド元素であるウラン元素を含む超伝導は、これまでに見つかっている超伝導体の中でも最も異常な超伝導・磁気特性を持つといっても過言ではなく、従来の遍歴3d 電子系や局在4f 電子系の物理の枠組みでは捉えられない重要な学術的位置を占めている。特に、30年以上も未解明であったUBe13, (U,Th)Be13の超伝導対称性に関する成果は非常に高い学術的価値がある。
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