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2011 Fiscal Year Final Research Report

Study of the FFLO state with Anomalous Vortices in CeCoIn5

Research Project

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Project/Area Number 20340082
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Research Field Condensed matter physics II
Research InstitutionHokkaido University

Principal Investigator

KUMAGAI Ken-ichi  北海道大学, 名誉教授 (70029560)

Project Period (FY) 2007 – 2011
Keywords強相関係
Research Abstract

The quasi-two dimensional heavy fermion superconductor CeCoIn_5 continues to excite great interest, because it shows a number of fascinating superconducting properties. CeCoIn_5 is an extremely clean high-κ superconductor with d-wave symmetry. The superconductivity of CeCoIn_5 at high fields is destroyed by Pauli paramagnetic effect, as evidenced by the first-order phase transition at the upper critical field H_c2. Closely related to the Pauli limited superconductivity, this high-field and low-temperature phase (HL-phase) has been attributed to the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state. The presence of the FFLO state in CeCoIn5 has been supported by several experiments. However, recent NMR and neutron data in parallel field demonstrated a long-range static magnetic order in the HL-phase. Remarkably this incommensurate spin-density wave order vanishes when the superconductivity dies at H_c2, indicating that the magnetism and the exotic superconductivity are closely intertwined.
In this study, to improve our understanding of how the exotic superconductivity and magnetism can interact in CeCoIn_5, we measured NMR spectra on the three distinct In sites. ^<115>In NMR measurements demonstrate the emergence of a spatially distributed normal quasiparticle region in the HL-phase in parallel field. The field evolution of the paramagnetic magnetization and low energy quasiparticle DOS can be described well by the order parameter associated with the nodal plane formation via the FFLO second order phase transition. The NMR spectra also reveal that the spatially uniform SDW coexists with the FFLO nodal planes. The exotic HL-phase is suppressed with increasing the angle of the direction of magnetic field with respect to the a-axis, and disappears beyond θ~20°.
Our results provide strong evidence for the formation of the FFLO state via the second order phase transition, which coexists with the static magnetic order.

  • Research Products

    (16 results)

All 2012 2011 2010 2009 2008

All Journal Article (3 results) Presentation (13 results)

  • [Journal Article] Evolution of Paramagnetic Quasiparticle Excitations Emerged in the High-Field Superconducting Phase of CeCoIn_52011

    • Author(s)
      K. Kumagai, H. Shishido, T. Shibauchim Y.Matsuda
    • Journal Title

      Phys. Rev. Lett.

      Volume: 106 Pages: 137004

  • [Journal Article] NMR Study of Magnetically-Ordered State in a Novel Superconducting Phase in CeCoIn_52010

    • Author(s)
      K. Kumagai, N. Kondoh, H. Shishido, Y.Matsuda
    • Journal Title

      Physica C

      Volume: 470 Pages: 533-535

  • [Journal Article] NMR study of a FFLO state of CeCoIn_5 in a Perpendicular and a Parallel Field2008

    • Author(s)
      K. Kumagai, T. Oyaizu, Y. Furukawa, H.Shishido and Y. Matsuda
    • Journal Title

      Physica B

      Volume: 403 Pages: 1144-1146

  • [Presentation] NMR Study of Magnetic Order and Spatially-Modulated Superconducting Gap in CeCoIn_52012

    • Author(s)
      K. Kumagai, H. Shishido, T. Shibauchi and Y. Matsuda
    • Organizer
      International Conference of Magnetism and Superconductivity (ICSM2012)
    • Place of Presentation
      Istanbul, Turkey
    • Year and Date
      20120427-0504
  • [Presentation] NMR Study of Magnetic Order and the FFLO State in CeCoIn_52011

    • Author(s)
      K. Kumagai
    • Organizer
      新学術領域研究「重い電子系の形成と秩序化」ワークショップ
    • Place of Presentation
      新潟大学
    • Year and Date
      20111111-12
  • [Presentation] NMR Study of Magnetic Order and Spatially-Modulated Superconducting Gap in CeCoIn_52011

    • Author(s)
      K. Kumagai, H. Shishido, T. Shibauchi and Y.Matsuda
    • Organizer
      A special session on the application of μSR, NMR and LTXRD etc in condensed matter, Fall Meeting of Chinese Physical Society
    • Place of Presentation
      Hangzhou, China
    • Year and Date
      20110916-18
  • [Presentation] NMR Study of Magnetic Order and Spatially-Modulated Superconducting Gap inCeCoIn_52011

    • Author(s)
      K. Kumagai, H. Shishido, T. Shibauchi and Y.Matsuda
    • Organizer
      International Conference of Strongly Correlated Electron Systems
    • Place of Presentation
      Cambridge, UK
    • Year and Date
      20110829-0903
  • [Presentation] Field Evolution of the FFLO Stateand Magnetism in CeCoIn_52011

    • Author(s)
      K. Kumagai, H. Shishido, T. Shibauchi and Y.Matsuda
    • Organizer
      International Conference on Ultra Low Temperature Physics
    • Place of Presentation
      KAIST, Daejeon, Republic of Korea
    • Year and Date
      20110819-22
  • [Presentation] ^<27>Al-and ^<95>Mo-NMR Study on Noncentrosymmetric Superconductor Mo_3A_2C2011

    • Author(s)
      K. Kumagai, H. Shishido, T. Shibauchi and Y. Matsuda
    • Organizer
      26th International Conference on Low Temperature Physics
    • Place of Presentation
      Beijing, Chaina
    • Year and Date
      20110810-17
  • [Presentation] NMR Study of the FFLO State and Magnetism in CeCoIn_52011

    • Author(s)
      K. Kumagai, H. Shishido, T. Shibauchi and Y. Matsuda
    • Organizer
      26th International Conference on Low Temperature Physics
    • Place of Presentation
      Beijing, Chaina
    • Year and Date
      20110810-17
  • [Presentation] NMR study of magnetic order and FFLO state in CeCoIn_52010

    • Author(s)
      K. Kumagai, H. Shishido, and Y. Matsuda
    • Organizer
      International Conference on Strongly Correlated Electron Systems
    • Place of Presentation
      Santa Fe, USA
    • Year and Date
      20100627-0702
  • [Presentation] NMR Study of Magnetic Order and Spatially-Modulated Superconducting Gap in CeCoIn_52010

    • Author(s)
      K. Kumagai, H. Shishido, and Y. Matsuda
    • Organizer
      International Conference on Spectroscopes in Novel Superconductors
    • Place of Presentation
      Shanghai, China
    • Year and Date
      20100524-28
  • [Presentation] NMR Study of Magnetically-Ordered Stateand Spatially-Modulated Superconducting Gapin CeCoIn_52010

    • Author(s)
      K. Kumagai, H. Shishido, and Y. Matsuda
    • Organizer
      International Conference on Superconductivity and Magnetism
    • Place of Presentation
      Antalya, Turkey
    • Year and Date
      20100425-30
  • [Presentation] Magnetic Order inside the FFLO Phase in CeCoIn_52009

    • Author(s)
      K Kumagai
    • Organizer
      NATO Advanced Research Workshop on Physical Properties of Nano Systems, Yalta
    • Place of Presentation
      Ukraine, September
    • Year and Date
      20090929-1002
  • [Presentation] NMR study of magnetic and superconducting order of CeCoIn_5 in a high field and low temperature phase2009

    • Author(s)
      K. Kumagai, N. Kondoh, H. Shishido, and Y. Matsuda
    • Organizer
      12th International Workshop on Vortex Matter in Superconductors
    • Place of Presentation
      Yamanaka Naito Seminar House, Lake Yamanaka, Japan
    • Year and Date
      20090912-16
  • [Presentation] NMR Study of Magnetically-Ordered State in a Novel Superconducting Phase in CeCoIn_52009

    • Author(s)
      K. Kumagai, N. Kondoh, H. Shishido, and Y. Matsuda
    • Organizer
      9th International Conference on Materials and Mechanisms of Superconductivity
    • Place of Presentation
      Tokyo
    • Year and Date
      20090907-12

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Published: 2013-07-31  

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