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Superconductor-Insulator Transition in disordered 2D-Superconductor

Research Project

Project/Area Number 04452038
Research Category

Grant-in-Aid for General Scientific Research (B)

Allocation TypeSingle-year Grants
Research Field 固体物性
Research InstitutionDeot. of Physics, Tokyo Institute of Technology

Principal Investigator

NISHIDA Nobuhiko  Tokyo Institute of Technology, Dept. of Physics, Professor, 理学部, 教授 (50126140)

Co-Investigator(Kenkyū-buntansha) OKUMA Satoshi  Tokyo Institute of Technology, Cryogenic Reseach Center, Associate Professor, 極低温システム研究センター, 助教授 (50194105)
Project Period (FY) 1992 – 1994
Project Status Completed (Fiscal Year 1994)
Budget Amount *help
¥8,200,000 (Direct Cost: ¥8,200,000)
Fiscal Year 1994: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1993: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1992: ¥6,700,000 (Direct Cost: ¥6,700,000)
Keywordssuperconductor-insilator transition, / Kosterlitz-Thouless transition, / 2D-superconductors / amorphous superconductors, / superconducting fluctuations / 近接効果 / Kostelitz-Thouless転移 / 超伝導揺らぎ / Kosterlitz-Thouless転移 / グラニュラー超伝導体 / Kosteritz-Thouless転移 / アモルファス超伝導膜
Research Abstract

In a 2D superconducting system a superconductor-insulator transition occuras at absolute zero as disorderness is increased. We have studied this problem in amorphous Nb ultra-thin films system which are prepared by quecnch-condensation of Nb on a cold Al_2O_3 substarate of liquid helium temperanture. We were able to prepare a-Nb films with thickness from about 3 - 4 * with and the thickness was able to varied in a fine steo of 0.1 *. Furtermore, we have developed a technique to measure electrical resistances of a-Nb thin films in situ in high vacuum and at tempertaures down to 1.6 K.Mean field superconducting transition temperatures (T_<c0>) and Kosterlitz-Thouless transition temperatures (T_<KT>) have been measured with varying film thickness. It has been found that both T_<CO> and T_<KT> decrease with decreasing film thickness, but T_<KT> seems to vanish faster than T_<c0>. This is the first measurement of the dependence of T_<KT> on the thickness of superconducting films. The fast vanishing of T_<KT> means that at absolute zero we have found a new phase where cooper pair exists in the 2D superconducting film, but global phase coherence is absent. This result has been reported in 20 th. Int Conf. on low temperature physics (Eugene, 1993) and reported as a doctor thesis of Atsushi Asamitsu in March of 1994 at Tokyo Institute of Technology. To confirm this result, experiments at temperatures below 1 K are now in progress.

Report

(4 results)
  • 1994 Annual Research Report   Final Research Report Summary
  • 1993 Annual Research Report
  • 1992 Annual Research Report
  • Research Products

    (13 results)

All Other

All Publications (13 results)

  • [Publications] A.Asamitsu and N.Nishida: "Disappearance of Superconductivity in Ultra-Thin Amorphous Nb Films" Physica B. 194-196. 1649-1650 (1994)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1994 Final Research Report Summary
  • [Publications] 井口学 他2名: "アモルファスNb超薄膜の超伝導-絶縁体転移:超伝導ゆらぎと電子局在" 日本物理学会講演概要集(49回年会). 3. 437-437 (1994)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1994 Final Research Report Summary
  • [Publications] 朝光敦 他2名: "アモルファスNb超薄膜の超伝導-絶縁体転移:コスタリッツ-サウレス転移" 日本物理学会講演概要集(49回年会). 3. 437-437 (1994)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1994 Final Research Report Summary
  • [Publications] 松葉健 他4名: "Ag,Cu/アモルファスNb超薄膜の近接効果" 日本物理学会講演概要集(50回年会). 3. 471-471 (1995)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1994 Final Research Report Summary
  • [Publications] A.Asamitsu, M.Iguchi, A.Ichikawa and N.Nishida: "Disappearance of Superconductivity in Ultra Thin Amorphous Nb films" Physica. 1649. B194-196 (1994)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1994 Final Research Report Summary
  • [Publications] A.Asamitsu: "Disappearance of Superconductivity in Ultra Thin Amorphous Nb Films" Doctor Thesis Tokyo Institute of Technology. (1994)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1994 Final Research Report Summary
  • [Publications] A.Asamitsu and N.Nishida: "Disappearance of Superconductivity in Ultra-Thin Amorphous Nb Films" Physica B. 194-196. 1649-1650 (1994)

    • Related Report
      1994 Annual Research Report
  • [Publications] 井口学,他2名: "アモルファスNb超薄膜の超伝導-絶縁体転移:超伝導ゆらぎと電子局在" 日本物理学会講演概要集(49回年会). 3. 437-437 (1994)

    • Related Report
      1994 Annual Research Report
  • [Publications] 朝光敦,他2名: "アモルファスNb超薄膜の超伝導絶縁体転移:コスタリッツ-サウレス転移" 日本物理学会講演概要集(49回年会). 3. 437-437 (1994)

    • Related Report
      1994 Annual Research Report
  • [Publications] 松葉健,他4名: "Ag,Cu/アモルファスNb超薄膜の近接効果" 日本物理学会講演概要集(50回年会). (印刷中). (1995)

    • Related Report
      1994 Annual Research Report
  • [Publications] 朝光敦 他3名: "Nb超薄膜の磁場中での絶縁体-超伝導転移II" 日本物理学会年会講演予稿集. 3. (1993)

    • Related Report
      1993 Annual Research Report
  • [Publications] A.Asamitsu and N.Nishida: "Disappearance of Superconductivity in Ultra-Thin Amorphous Nb Films" Physica B. (in press). (1994)

    • Related Report
      1993 Annual Research Report
  • [Publications] 朝光敦,西田信彦: "Nb超薄膜の磁場中での絶縁体-超伝導転移" 日本物理学科秋の分科会講演予稿集. 3. (1992)

    • Related Report
      1992 Annual Research Report

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Published: 1992-04-01   Modified: 2016-04-21  

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