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梯子型格子を持つ系の超伝導-その物性の解明と新しい系の探索

Research Project

Project/Area Number10440113
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Research Field 固体物性II(磁性・金属・低温)
Research InstitutionAoyama Gakuin University

Principal Investigator

AKIMITSU Jun  College of Science and Engineering, Aoyama Gakuin University, Professor, 理工学部, 教授 (80013522)

Co-Investigator(Kenkyū-buntansha) NAKADA Hisaho  College of Science and Engineering, Aoyama Gakuin University, Assistant, 理工学部, 助手 (30286231)
上原 政智  青山学院大学, 理工学部, 日本学術振興会特別研
Project Period (FY) 1998 – 1999
Project Status Completed(Fiscal Year 1999)
Budget Amount *help
¥14,800,000 (Direct Cost : ¥14,800,000)
Fiscal Year 1999 : ¥4,500,000 (Direct Cost : ¥4,500,000)
Fiscal Year 1998 : ¥10,300,000 (Direct Cost : ¥10,300,000)
KeywordsSuperconductivity / Cu oxide / Ladder compound / Spin gap
Research Abstract

Recently, the ladder system which consists of two coupled spin-1/2 chains was proposed as an interesting intermediate step between one-and two-dimensional systems. Dagotto et al. and Rice et. Al. predicted that hole-doping in a spin-ladder system might produce the metallic state with a spin gap and give rise to novel superconductivity.
To examine the theoretical prediction, carrier doping to SrィイD214xィエD2CaィイD2xィエD2CuィイD224ィエD2OィイD241ィエD2, being composed of CuィイD22ィエD2OィイD23ィエD2 planes with two-leg ladders, has been performed. We discovered that heavily Ca-substituted compound (x=13.6) showed superconductivity under pressure (TィイD2cィエD2(onset)〜l2K at 3.5 Gpa). To discuss the superconductivity further, the single crystal measurements have been made. Superconductivity was observed between 3.5 Gpa and 8 Gpa (TィイD2cィエD2 (onset)〜9K at 4.5GPa), accompanied by metallic resistivity between the ladders. This results strongly suggests that the application of pressure brings about a crossover from … More one-to two-dimensional and the system is anisotropic two-dimensional at the optimum pressure for the superconducting transition.
To discuss the relationship between spin gap and the superconductivity, we carried out the inelastic neutron scattering experiment for SrィイD22.5ィエD2CaィイD211.5ィエD2CuィイD224ィエD2OィイD241ィエD2 single crystal. The spin gap energy for the ladder is found to be 32.1meV and the exchange coupling was estimated to be 90 meV (along the ladders) and 65 meV (along the rung).
Specific heat, magnetic susceptibility and neutron scattering measurements were performed on SrィイD214xィエD2CaィイD2xィエD2CuィイD224ィエD2OィイD241ィエD2 single crystals. The specific heat of Ca-substituted samples SrィイD214xィエD2CaィイD2xィエD2CuィイD224ィエD2OィイD241ィエD2 showed a sharp phase transition at about 3 K. By the measurements of the magnetic susceptibility, it was confirmed that the phase transition was originated from antiferromagnetic long-range order. Besides, the several magnetic Bragg peaks were observed by neutron scattering measurement, and a possible magnetic structure on the chain and ladder sites were determined. In this system, the singlet state and antiferromagnetic order induced by appropriate hole-doping coexist at ambient pressure. Less

Report

(3results)
  • 1999 Annual Research Report   Final Research Report Summary
  • 1998 Annual Research Report

Research Products

(14results)

All Other

All Publications

  • [Publications] 秋光純、永田貴志: "梯子格子系の超伝導と磁性"固体物理. Vol.34. 159-171 (1999)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] T. Nagata et al: "Antiferromagnetic Ordering in the Spin Singlet State on thet Ladder/Chain Material"J. Phys. Soc. Jpn.. Vol.68. 2206-2209 (1999)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] J. Akimitsu et al: "Spin and Charge Dynamics in the Hole-Doped Two-Leg Ladder Compound Sr_<14-X>Ca_XCu_<24>O_<41>"Phys. Chem. Trans. Met. Oxi.. 125. 289-298 (1999)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] T.Nagata et al.: "Antiferromagnetic Ordering in the Spin Singlet State on that Ladder/Chain Material"J.Phys.Soc.Jpn. 68. 2206-2209 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] J.Akimitsu et al.: "Spin and Charge Dynamics in the Hole-Doped Two-Leg Ladder Compound SrィイD214-xィエD2CaィイD2xィエD2CuィイD224ィエD2OィイD241ィエD2"Phys.Chem.Trans.Met.Oxi.. 125. 289-298 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] T.tagata et al.: "Coexistence of the spin liquid state and the magnetic ordering in the spin ladder compound SrィイD214-xィエD2CaィイD2xィエD2CuィイD224ィエD2OィイD241ィエD2"J.Phys.Chem.Solids. 60. 1109-1111 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] 秋光 純 永田 貴志: "梯子格子系の超伝導と磁性"固体物理. Vol.34. 159-171 (1999)

    • Related Report
      1999 Annual Research Report
  • [Publications] J.Akimitsu et al.: "Spin and Charge Dynamics in the Hole-Doped Two-Leg Ladder Compound Sr_<14-X>Ca_XCu_<24>O_<41>"Phys.Chem.Trans.Met.Oxi.. 125. 289-298 (1999)

    • Related Report
      1999 Annual Research Report
  • [Publications] K.Magishi et al.: "Spin gap and dynamics in Sr_<14-x>Ca_xCu_<24>O_<41> comprising hole-doped two-leg spin ladders:Cu NMR study on single crystals" Phys.Rev.B. Vol.57 No.18. 11533-11544 (1998)

    • Related Report
      1998 Annual Research Report
  • [Publications] T.Nakanishi et al.: "High-Pressure Transport Properties of the Superconducting Spin-ladder System Sr_<14-x>Ca_xCu_<24>O_<41+δ>," J.Phys.Soc.Jpn. Vol.67 No.7. 2408-2414 (1998)

    • Related Report
      1998 Annual Research Report
  • [Publications] M.Tamura et al.: "A new superconductor with 1222 structure (Cu_<1-x>M_x)Sr_2(Y_<1-y>Ce_y)_2Cu_2O_δ(M=Ti,V,Cr,Fe,Co,Ga,Ge,Mo,Ce,W and Re)" Physica C. Vol.33 No.1&2. 1-10 (1998)

    • Related Report
      1998 Annual Research Report
  • [Publications] T.Nagata et al.: "Pressure-induced dimensional crossover and superconductivity in the hole-doped two-leg ladder compound Sr_<14-x>Ca_xCu_<24>O_<41>" Phys.Rev.Lett.Vol.81. 1090-1093 (1998)

    • Related Report
      1998 Annual Research Report
  • [Publications] R.S.Eccleston et al.: "The Spin Dynamic of the Spin Ladder,Dimer Chain Material Sr_<14>Cu_<24>O_<41>" Phys.Rev.Lett.Vol.81 No.8. 1702-1705 (1998)

    • Related Report
      1998 Annual Research Report
  • [Publications] S.Katano et al.: "Neutron Scattering Study of the Spin Gap in the Hole-Doped Spin Ladder System(Sr_<2.5>Ca_<11.5>Cu_<24>O_<41>" Phys.Rev.Lett.82. 636-639 (1999)

    • Related Report
      1998 Annual Research Report

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Published : 1998-04-01   Modified : 2016-04-21  

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