Control of superconductivity by noncollinear magnetism

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K13883
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 13030:Magnetism, superconductivity and strongly correlated systems-related
• Research Institution: Kyoto University
• Principal Investigator: Narita Hideki 京都大学, 化学研究所, 特定助教 (80846709)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 超伝導 / ノンコリニア磁性 / 強相関電子系 / スピントロニクス

Outline of Final Research Achievements

In this study, we have prepared samples containing ferromagnets, superconductors, and heavy metals to control magnetism and superconductivity toward the control of superconductivity by non-collinear magnetic structures.
As a result, we succeeded in observing the superconducting diode effect in ferromagnetic/superconducting multilayers with broken spatial inversion symmetry, in which the critical current is non-reciprocal depending on the magnetization and current direction of the ferromagnet at zero magnetic field. The complex non-reciprocal critical current behavior suggests that it reflects the complexity of the magnetic domains.
The results also suggest that the control of magnetic domain and band structure asymmetry is effective in controlling superconductivity.

Free Research Field

物性物理学

Academic Significance and Societal Importance of the Research Achievements

ノンコリニア磁性と超伝導の共存に向けて作製した空間反転対称性の破れた強磁性/超伝導積層膜において、ゼロ磁場超伝導ダイオード効果が観測された。この成果により、ゼロ磁場で超伝導状態のON/OFFが可能となった。したがって、さらにノンコリニア磁性の自由度を導入することは、制御パラメータが増えるだけでなく、漏洩磁場による素子特性の低下を抑制し、超伝導素子の集積化にも有利となることが期待される。また、磁気ドメインやバンド構造の非対称性が超伝導の制御に有効であることを示唆する結果を得たことは、新奇な超伝導素子開発の設計指針となる。