Spin current as a probe for spin excitations in high temperature superconducting materials

2020 Fiscal Year Final Research Report

• Project/Area Number: 19K23414
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0202:Condensed matter physics, plasma science, nuclear engineering, earth resources engineering, energy engineering, and related fields
• Research Institution: Tohoku University
• Principal Investigator: Lustikova Jana 東北大学, 先端スピントロニクス研究開発センター, 助教 (90847964)
• Project Period (FY): 2019-08-30 – 2021-03-31
• Keywords: 超伝導 / 銅酸化物 / 鉄系超伝導 / スピン流 / スピントロニクス / スピン注入

Outline of Final Research Achievements

The role of spin excitations in the appearance of superconductivity in high-temperature superconductors has been long discussed. In this study, we aim to observe spin excitations in high-temperature superconducting materials by the injection of spin current. The samples are high-temperature cuprates and iron-based superconductors coated with a thin film of ferromagnetic metal. By applying microwaves to the ferromagnetic coating, spin current injected into the superconductor material is estimated from the magnetic damping constant. As a result, we observed a change in damping constant close to the superconducting transition temperature in cuprate materials and below the structural transition temperature in iron-based materials. We have considered the origin of this effect.

Free Research Field

スピントロニクス

Academic Significance and Societal Importance of the Research Achievements

高温超伝導物質の中では、高温超伝導銅酸化物及び鉄系超伝導体の超伝導転移温度が最も高い。両者におけるスピン励起の超伝導状態との関係について共通点及び相違点を明らかにすることによって、超伝導転移温度の向上に向けた物質設計指針が得られると期待されている。本研究の学術的意味は高温超伝導物質のスピン物性プローブとしてスピン流に注目することにある。中性子散乱や核磁気共鳴など従来の実験手法とは異なるエネルギーや長さスケールをプローブし、高温超伝導体におけるスピン励起の多角的理解に貢献する。