Interplay between superconductivity and pseudogap state studied by STM/STS and time-resolved optical spectroscopy

2022 Fiscal Year Final Research Report

• Project/Area Number: 19K03732
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 13030:Magnetism, superconductivity and strongly correlated systems-related
• Research Institution: Hokkaido University
• Principal Investigator: Oda Migaku 北海道大学, 理学研究院, 教授 (70204211)
• Co-Investigator(Kenkyū-buntansha): 戸田 泰則 北海道大学, 工学研究院, 教授 (00313106)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: 銅酸化物高温超伝導 / STM/STS / ポンププローブ時間分解分 / 擬ギャップ / 電子系変調構造 / 反強磁性秩序

Outline of Final Research Achievements

In this study, we performed scanning tunneling microscopy/spectroscopy and pump-probe time-resolved optical spectroscopy on single crystals of bismuth-based high-temperature cuprate superconductors, and examined the real-space correlation among three types of electronic modulations (d form factor density wave and checkerboard modulation in the antinodal region, which is responsible for pseudogap, quasiparticle interference modulation in the Fermi-arc region, which is responsible for superconductivity), and the time-space correlation between pseudogap state and superconductivity in their formation process. On the basis of the results obtained in this study, we have suggested that the origin of checkerboard modulation will be the pair density wave, and clarified that the antinodal electronic states responsible for the pseudogap will be involved in the occurence of high-temperature superconductivity.

Free Research Field

固体電子物性

Academic Significance and Societal Importance of the Research Achievements

銅酸化物高温超伝導体は、その発見当初から従来の超伝導発現機構とは異なる新しいメカニズムの可能性が指摘され、学術的に大きな注目を集めてきた。また、エネルギー産業への応用の可能性など、社会的な意義も大きい。本研究では、高温超伝導がクーパー対密度波や擬ギャップを伴ったｄ構造因子密度波という新奇な密度波状態と実空間の同一領域で共存していることに加え、このような電子状態が高温超伝導の発現に関わっている可能性が示された。これらの研究成果は高温超伝導のメカニズムの解明に繋がるものであり、このことが本研究の学術的意義と言える。