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2006 Fiscal Year Final Research Report Summary

Thermal Study of phase transition for π-d organic conductor under pressure

Research Project

Project/Area Number 15340123
Research Category

Grant-in-Aid for Scientific Research (B)

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

Principal Investigator

NISHIO Yutaka  Faculty of Science, Professor, 理学部, 教授 (20172629)

Co-Investigator(Kenkyū-buntansha) KAJITA Koji  Faculty of Science, Professor, 理学部, 教授 (50011739)
Project Period (FY) 2003 – 2006
KeywordsSpecific heat / Phase Transition / Organic Metal / Hydrostatic Pressure / Uniaxial Pressure / Latent heat / Charge Ordering / Super conductivity
Research Abstract

Many materials in organic conductor undergo low dimensional characteristic phase transitions, for example, CDW, SDW, spin-Peierls, some magnetic ordering, superconductivity and so on with strong electron-electron interaction. We have developed specific heat measurement system in the wide temperature range between 5K and 300K for the sample with the weight of 0.3mg with relative accuracy of 0.1% to quantitatively discuss the above phase transitions. We succeeded in the measurements of 1st order phase transition in the cooling and heating processes by a method based on DTA (Differential Thermal Analysis). We summarized following results.
1. (DMe-DCNQI)_2Cu system・Deuterium degrees of freedom in methyl basis: Specific heat measurements are systematically performed for the systems having various methyl bases of CH_3, CH_2D, CHD2_and CD_3. In these systems, we discovered the anomalous specific heat due to deuterium degrees of freedom. We systematically clarified the specific heat of selectiv … More ely deuterated methyl bases in the (DMe-DCNQI)_2Cu system. Under equilibrium condition, these systems do not show the sharp peak induced by the phase transition, but exhibit the Schottky type specific heat in the systems having CH_2D and CHD_2 bases. Their energy schemes are determined only by the position of the deuterium atom in the methyl bases.
2. A new type phase transition for the system of Et_2Me_2Sb[Pd(dmit)_2]_2: In this transition, Pd(dmit)^2. having localized magnetic moments s=1/2 change into neutral Pd(dmit)_2^0. and divalent Pd(dmit)_2^2-spin-less states. We have studied the thermal properties of this system and observed a broad hump above critical temperature as well as the sharp peak with small hysteresis in the vicinity of the phase transition. Resulting total entropy absorbed around the transition region reaches to 13J/molK, which is largest value in the organic systems exhibiting charge ordering transitions. We found that spin freedom and lattice modulation cooperatively drive these new type phase transition.
3. Mysterious metal-insulator transition induced by a charge ordering for θ-(BEDT-TTF)_2RbZn(SCN)_4: These anomalies at the phase transition have large temperature hysteresis and show different shapes of the peak, huge and sharp peak in heating process and broad hump in cooling process. We observed anomalous specific heat caused by this phase transition and discussed quantitatively degrees of freedom of this transition. Less

  • Research Products

    (8 results)

All 2007 2006

All Journal Article (8 results)

  • [Journal Article] Hexagonal Supramolecular Architecture from Ferrocenium Cations Incorporation [Ni(mnt)2]- Colimns2007

    • Author(s)
      T.Mochida
    • Journal Title

      Chemistry A European Journal 13

      Pages: 1872-1881

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] HexagonalSupramolecularArchitecturefrom Ferrocenium Cations Incorporation Ni (mnt)2]-Colimns2007

    • Author(s)
      T.Mochida
    • Journal Title

      Chemistry A European Journal Vol. 13

      Pages: 1872-1881

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Out-of-Plane Resistance under Transverse Magnetic Field in Quasi-One-Dimensional Layered Metals2006

    • Author(s)
      Shigeharu. Sugawara
    • Journal Title

      Journal of the Physical Society of Japan 75

      Pages: 053704-053708

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Electronic Phases in an Organic Conductor α-(BEDT-TTF)2I3 : Ultra Narrow Gap Semiconductor, Superconductor, Metal, and Charge-Ordered Insulator2006

    • Author(s)
      Naoya Tajima
    • Journal Title

      Journal of the Physical Society of Japan 75

      Pages: 051010-051019

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Out-of-Plane Resistance of Quasi-Two Dimensional Metal (BEDT-TTF)3C1(DFBIB) in Transverse Magnetic Fields2006

    • Author(s)
      Riki Jindo
    • Journal Title

      Journal of the Physical Society of Japan 75

      Pages: 013705-013709

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Out-of-Plane Resistance under Transverse Magnetic Field in Quasi-One-Dimensional Layered Metals2006

    • Author(s)
      Shigeharu.Sugawara
    • Journal Title

      Journal of the Physical Society of Japan Vol. 75

      Pages: 053704-08

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Electronic Phases in an Organic Conductor α-(BEDT-TTF)2I3 : Ultra Narrow Gap Semiconductor, Superconductor, Metal, and Charge-Ordered Insulator2006

    • Author(s)
      Naoya Tajima
    • Journal Title

      Journal of the Physical Society of Japan Vol. 75

      Pages: 051010-19

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Out-of-Plane Resistance of Quasi-Two Dimensional Metal (BEDT-TTF)3C1(DFBIB) in Transverse Magnetic Fields2006

    • Author(s)
      Riki Jindo
    • Journal Title

      Journal of the Physical Society of Japan Vol. 75

      Pages: 013705-09

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 2008-05-27  

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