Elsidation of mechanism for supermodulation and superconductivity in BiCh2 compounds by bulk/nano measurements

2019 Fiscal Year Final Research Report

• Project/Area Number: 18K13505
• 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: Nihon University
• Principal Investigator: DEMURA Satoshi 日本大学, 理工学部, 助手 (90734939)
• Project Period (FY): 2018-04-01 – 2020-03-31
• Keywords: 超伝導 / BiCh2系超伝導 / 走査型トンネル顕微鏡 / 電荷密度波 / 超伝導ギャップ / 磁束量子

Outline of Final Research Achievements

In this research, we investigated a relationship between superconductivity and supermodulation observed in BiCh2(Ch=S,Se) compounds and try to reveal mechanism of these phenomenon.At first,supermodulation was successfully observed in surface of LaO1-xFxBiSe2 (x=0.1) by scanning tunneling microscopy and spectroscopy (STM/STS) observation. This structure has similar features in previous STM/STS results for a sample with x=0.5. This result suggests that the mechanism of this structure is not explained by Peierls scenario.Furthermore,partial Sn substitution to LaO1-xFxBiS2 was found to enhance superconducting properties.By using this samples, the first observation of magnetic vortices in BiCh2 compounds was succeeded. This result expects to lead to the elucidation of the mechanism of the superconductivity in BiCh2 compounds.

Free Research Field

超伝導

Academic Significance and Societal Importance of the Research Achievements

本研究では、BiCh2(Ch=S,Se)系化合物において発現する超周期構造と超伝導の相関性を調査した。BiCh2(Ch=S,Se)系化合物は現在世界的に注目されている物質である。今回の研究では、この物質において発現する超周期構造がパイエルス型の構造でなく、超伝導とも共存する可能性があることを明らかにした。また、本系で磁束量子観測も出来る試料の合成に世界で初めて成功した。そのため本研究の成果から、世界的に注目されている物質の超伝導機構の解明につながることが期待される。