Relationship between novel electronic ordered states and superconductivity in iron-based superconductors

2019 Fiscal Year Final Research Report

• Project/Area Number: 18K13500
• 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: Osaka University
• Principal Investigator: NAKAJIMA Masamichi 大阪大学, 理学研究科, 助教 (20724347)
• Project Period (FY): 2018-04-01 – 2020-03-31
• Keywords: 鉄系超伝導体 / 単結晶育成 / 電子ネマティック状態 / 弾性抵抗率

Outline of Final Research Achievements

Among iron-based superconductors, Ba1-xKxFe2As2 exhibits a unique electronic phase diagram. To investigate the relationship between normal-state electronic states and superconductivity, we performed elastoresistivity and x-ray diffraction measurements on Ba1-xKxFe2As2 single crystals. Elastoresistivity, resistive response to strain, enables us to obtain nematic susceptibility, which is an important physical quantity when discussing an electronic nematic state with rotational symmetry breaking. We revealed from the temperature dependence of nematic susceptibility that the electronic nematic state plays a crucial role in emergence of superconductivity. From the x-ray diffraction measurement, we observed a diffraction peak which is considered to be related with a novel electronic order. This electronic order seems to have an intimate involvement in the occurrence of superconductivity.

Free Research Field

高温超伝導

Academic Significance and Societal Importance of the Research Achievements

電子が強く相関している系では、制御パラメータを振ることにより様々な秩序相が現れるので、豊かな電子相図が描かれる。それぞれの秩序相の関係性が明らかになれば、どのような状況で面白い物性が現れるのかを知ることができるため、機能性材料の開発につながる可能性もある。本研究では、複雑な電子相図を示す鉄系超伝導体を対象として、超伝導と深い関係があると考えられている秩序相について調べた。これにより、鉄系超伝導体で発現する超伝導に対する理解が深まった。今後、超伝導転移温度の高い超伝導体開発の指針を得ることができれば、応用面でも貢献できると考えられる。