Elucidating novel physical properties in the coexisting phase of magnetic order and superconductivity

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K14666
• 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: Japan Atomic Energy Agency
• Principal Investigator: Murai Naoki 国立研究開発法人日本原子力研究開発機構, 原子力科学研究部門 J－PARCセンター, 研究員 (90784223)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 非従来型超伝導 / 非弾性X線散乱 / 非弾性中性子散乱 / フォノン / スピン揺らぎ

Outline of Final Research Achievements

The discovery of high-Tc superconductivity in iron-based superconductors (FeSCs) has marked the beginning of a new era in superconductivity research. Many of the properties in FeSCs arise from an interplay of spin, orbital, and lattice degrees of freedom. A fundamental challenge in this context is to understand how such a complex interplay gives rise to emergent phenomena in FeSCs. Here, we performed extensive inelastic x-ray and neutron scattering studies that allow one to investigate the dynamical aspects of spin and lattice degrees of freedom. The results obtained in this study include (1) the effect of magnetism on phonon dispersion, (2) the observation of the multiple superconducting gaps in the neutron scattering response, and (3) the three-dimensional intensity modulation of the dynamical spin susceptibility and its relation to the Fermi surface nesting. Our work highlights the potential to use x-ray and neutron spectroscopy to investigate the complex electronic state of FeSCs.

Free Research Field

物性物理

Academic Significance and Societal Importance of the Research Achievements

鉄系超伝導体の諸物性を理解する上で，その磁性やフォノンの果たす役割を理解することは非常に重要である．本研究課題では，SPring-8とJ-PARCの最先端の分光技術を用いた物性計測を行うことで，鉄系超伝導体のスピン揺らぎ，フォノンに対する新しい知見が得られた．本研究に用いた手法は，銅酸化物や重い電子系等の他の物質の研究への拡張も可能であり，非従来型超伝導体の電子状態研究におけるX線・中性子分光法の適用領域を広げるものである．