Studies on the coexistence between superconductivity and antiferromagnetism by complementary use of precision measurements of magnetization and Josephson effect

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K03838
• 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: University of Hyogo
• Principal Investigator: Sumiyama Akihiko 兵庫県立大学, 理学研究科, 教授 (30226609)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 非従来型超伝導 / 反強磁性 / 直流磁化 / ジョセフソン効果

Outline of Final Research Achievements

For CePt3Si, in which superconductivity and antiferromagnetism coexist, the spontaneous magnetization that appears at the superconducting transition is observed even when antiferromagnetism disappears by applying pressure, which ensures that the spontaneous magnetization is not caused by antiferromagnetism. The result that the anomalous magnetic field dependence of Josephson critical current is not observed for the junction of reduced dimensions does not contradict with the local generation of spontaneous magnetization at the surface and/or the twin boundary.
For the heavy-fermion superconductor UPt3, the magnetic penetration depth in the plane perpendicular to the c-axis always shows linear temperature dependence at low temperatures, while the increase rate increases above the critical pressure where an antiferromagnetic correlation disappears, suggesting that the superconducting phase is modified

Free Research Field

低温物理学

Academic Significance and Societal Importance of the Research Achievements

最近多数発見されている、非従来型超伝導を示す物質群の超伝導の特異性を研究するための様々な手段のうち、磁場侵入長、ジョセフソン効果、自発磁化の測定を圧力下で行う技術を確立することができた。その応用として、通常は超伝導と磁性は競合するにもかかわらず、反強磁性と共存している非従来型超伝導体(CePt3Si, UPt3)について、圧力を印加して反強磁性を消失させることで、非従来型超伝導に対する磁性の影響についての知見が得られた。