Topological Josephson junction with arbitrary phase
| Project/Area Number |
17K18756
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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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| Research Field |
Condensed matter physics and related fields
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| Research Institution | Osaka University |
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Principal Investigator |
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| Project Period (FY) |
2017-06-30 – 2019-03-31
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| Project Status |
Completed (Fiscal Year 2018)
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| Budget Amount *help |
¥6,500,000 (Direct Cost: ¥5,000,000、Indirect Cost: ¥1,500,000)
Fiscal Year 2018: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2017: ¥5,200,000 (Direct Cost: ¥4,000,000、Indirect Cost: ¥1,200,000)
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| Keywords | ジョセフソン接合 / 超伝導材料・素子 / トポロジー / スピン蓄積 / 低温物性 / メゾスコピック系 |
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| Outline of Final Research Achievements |
In this work, we aimed 1) to verify that Bi/Ni bilayer is a topological superconductor by measuring the spin transport properties and 2) to demonstrate “Topological Josephson junction” with arbitrary phase using the Bi/Ni bilayer superconductor. We first performed spin transport measurements in Bi/Ni nanowires. The estimated spin diffusion length of Bi/Ni nanowires is 3 nm, which is shorter than that of thin Bi films. This result indicates that the Ni layer has a magnetic moment. The spin Hall signal in Bi/Ni below the superconducting transition temperature is enhanced by 1000 times compared to that above the transition temperature. In addition, it has a peculiar peak near the zero field, which has been never observed in an s-wave superconductor. We also fabricated Josephson junctions using the Bi/Ni bilayer superconductor. We are now investigating the relation between the critical current and the ferromagnetism of the Ni layer.
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| Academic Significance and Societal Importance of the Research Achievements |
現在様々な形で量子コンピュータの研究が進んでいるが、超伝導磁束量子回路で用いられている物質の多くがニオブNbをベースとしたs波超伝導体である。しかし、トポロジカル超伝導体を用いた量子デバイスを創製できれば、波動関数の位相制御という新しい機能を付与できる。これにより、超伝導量子コンピュータへの応用（コンパクト化や省エネルギー化）も期待される。さらに、量子力学の位相を積極的に利用した新しい位相物理学を切り開く可能性もある。
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Report
(3 results)
Research Products
(76 results)
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[Presentation] カイラル磁性体CrNb3S6薄膜における磁気輸送測定2019
Author(s)
川原遼馬, 谷口祐紀, 河上司, Y. A. Alaoui, 荒川智紀, 乾皓人, 島本雄介, 高阪勇輔, 戸川欣彦, 新見康洋, 小林研介
Organizer
日本物理学会第74回年次大会
Related Report
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[Presentation] Fabrication and electrical measurements of CrNb3S6 thin films2018
Author(s)
R. Kawahara, H. Taniguchi, T. Kawakami, Y. A. Alaoui, T. Arakawa, A. Inui, Y. Shimamoto, Y. Kosaka, Y. Togawa, Y. Niimi, and K. Kobayashi
Organizer
International Symposium on Chiral Magnetism (chi-mag 2018)
Related Report
Int'l Joint Research
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[Presentation] カイラル磁性体CrNb3S6薄膜における磁気抵抗測定2018
Author(s)
川原遼馬, 谷口祐紀, 河上司, Y. A. Alaoui, 荒川智紀, 乾皓人, 島本雄介, 高阪勇輔, 戸川欣彦, 新見康洋, 小林研介
Organizer
日本物理学会2018年秋季大会
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