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Magnetic-Field and Pressure Effects on the Magnetic Excitations in the Disordered Spin-Peierls Systems

Research Project

Project/Area Number 10640354
Research Category

Grant-in-Aid for Scientific Research (C)

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

Principal Investigator

SEKINE Tomoyuki  Sophia University, Department of Physics, Professor, 理工学部, 教授 (60110722)

Co-Investigator(Kenkyū-buntansha) KUROE Haruhiko  Sophia University, Department of Physics, Research Assistant, 理工学部, 助手 (40296885)
Project Period (FY) 1998 – 1999
Project Status Completed (Fiscal Year 1999)
Budget Amount *help
¥2,800,000 (Direct Cost: ¥2,800,000)
Fiscal Year 1999: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1998: ¥2,100,000 (Direct Cost: ¥2,100,000)
Keywordsspin-Peierls transition / magnetic excitation / Raman scattering / incommensurate phase / disordered system / magnetic-field effect / high-pressure effect / structural phase transition / 反強磁性
Research Abstract

1. Raman scattering in CuGeO_3
(1) In Zn-, Si- and Ni-doped CuGeO_3, we studied Raman scattering from the folded phonon, which was folded onto Γ point from the Brillouin zone boundary by the lattice dimerization, and found that the doping suppressed the spin-Peierls (SP) transition and reduced the lattice distortion. We also observed it even in the antiferromagnetic phase of the lightly doped samples, indicating the existence of the lattice dimerization in this phase. In the heavily doped samples its spectrum broadened with a higher-energy tail, indicating the existence of the uniform antiferromagnetic phase possessing a short-range lattice dimerization.
(2) Breakdown of the selection rule in the doped CuGeO_3 enabled us to observe a SP gap excitation. It decreased in energy and broadened with increasing dopant concentration. The two-magneticexcitation bound state changed into a resonant state and finally disappeared with increasing dopant concentration. These features were demonstrated … More theoretically by using Green's function, taking into account the shortening of the lifetime of the magnetic excitations.
(3) We studied the magnetic excitations in the incommensurate phase under high magnetic fields. In the incommensurate phase the SP gap excitation changed to a soliton-like excitation whose frequency increased with increasing magnetic field. On the other hand, the intensity of the two-magnetic-excitation bound/resonant state rapidly decreased.
(4) High-pressure equipment with a diamond anvil cell has been installed in order to study the high-pressure effect on the SP transition by means of Raman spectroscopy. We found successive structural phase transitions to the pyroxene-type structures under strictly hydrostatic pressures at room temperature. The pyroxene-type structures have already been reported to emerge in pure crystal only under quasihydrostatic pressures.
(5) It is well known that the SP phase disappears in heavily doped CuGeO_3. We demonstrated by observing the folded phonon that the SP phase revised in heavily Mg-doped crystal when the pressure was applied to it at low temperatures.
2. Raman scattering in α'-NaV_2O_5
(1) We observed three folded phonons and the first- and second-order Raman spectra from magnetic excitations in the low-temperature phase. We inferred the lattice symmetry of the low-temperature phase from the results of the polarization characteristics. The Na^+-ion deficiency in α'-Na_<1-δ>V_2O_5 cut the spin chain, and it suppressed the phase transition and reduced the lattice distortion. We compared these results with CuGeO_3.
(2) We observed the Fano effect between the V-O bending phonon and the d - d electronic Raman band of the V^<4+> ion. This effect weakened with increasing concentration of the Na^+-ion deficiency. These spectra were demonstrated theoretically, taking into account a phonon-phonon relaxation process. Less

Report

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

    (29 results)

All Other

All Publications (29 results)

  • [Publications] T.Sekine: "Spin-Peierls Gap and Two-Magnetic-Excitation Bound and Resonant states in Cu_<1-x>Zn_xGeO_3 and CuGe_<1-y>Si_yO_3"Journal of the Physical Society of Japna. 67巻. 1440-1450 (1998)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] H.Kuroe: "Raman Scattering in the Inorganic Soin-Peierls System α'-Na_<1-δ>V_2O_5"Journal of the Physical Society of Japan. 67巻. 2881-2892 (1998)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] H.Kuroe: "Spin-Peierls Transition in α'-NaV_2O_5 Observed by Raman Scattering"Physica B. 263-264巻. 803-805 (1999)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] H. Kuroe: "Raman Scattering in Zn-, Si- and Mg- Doped CuGeO_3"Physica B. 263-264巻. 825-828 (1999)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] H.Kuroe: "Folded Phonon Mode Observed by Raman Scattering in Zn- and Si- Doped CuGeO_3"Journal of the Physical Society of Japan. 68巻. 2046-2056 (1999)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] 黒江晴彦: "スピン・パイエルス物質CuGeO_3の光散乱"固体物理. 35巻. 105-119 (2000)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] H.Kuroe : "Raman and Luminescence Spectra in the Spin-Peierls System Cu_<1-x>Ni_xGeO_3"Physica B. 284-288巻. 1643-1644 (2000)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] T.Sekine: "Raman-Scattering Study of Doping Effects on the Structural Phase Transitions under Hydrostatic Pressures in CuGeO_3"Journal of the Physical Society of Japan. 70巻. 290-296 (2001)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] H.Kuroe: "Doping Effects on the Folded Phonon Mode in the Spin-Peierls Systems CuGeO_3 and α'-NaV_2O_5"J.Magn.Magn.Mater.. 171-181. 679-680 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] T.Sekine: "Raman Scattering from Magnetic Excitations in Zn- and Si- Doped CuGeO_3"J.Magn.Magn.Mater.. 171-181. 691-692 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] T.Sekine: "Spin-Peierls Gap and Two-Magnetic-Excitation Bound and Resonant States in Cu_<1-x>Zn_xGeO_3 and CuGe_<1-y>Si_yO_3"J.Phys.Soc.Jpn.. 67. 1440-1450 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] H.Kuroe: "Raman scattering in the Inorganic Spin-Peierls System α'-Na_<1-δ>V_2O_5"J.Phys.Soc.Jpn.. 67. 2881-2892 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] H.Kuroe: "Spin-Peierls Transition in α'-NaV_2O_5 Observed by Raman Scattering"Physica, B. 263&264. 803-805 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] H.Kuroe: "Raman Scattering in Zn-, Si- and Mg-Doped CuGeO_3"Physica, B. 263&264. 825-828 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] H.Kuroe: "Folded Phonon Mode Observed by Raman Scattering in Zn- and Si-Doped CuGeO_3"J.Phys.Soc.Jpn.. 68. 2046-2056 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] H.Kuroe: "Light Scattering in the Spin-Peierls Material CuGeO_3 (in Japanese)"Solid State Phys.. 35. 105-119 (2000)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] H.Kuroe: "Raman abd Luminescence Spectra in the Spin-Peierls System Cu_<1-x>Ni_xGeO_3"Physica, B. 284-288. 1643-1644 (2000)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] T.Sekine: "Ranan-Scattering Study of Doping Effects on the Structural Phase Transitions under Hydrostatic Pressures in CuGeO_3"J.Phys.Soc.Jpn.. 70. 290-296 (2001)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] T.Sekine: "Spin-Peierls Gap and Two-Magnetic-Excitation Bound and Resonant States in Cu_<1-x>Zn_xGeO_3 and CuGe_<1-y>Si_yO_3"Journal of the Physical of Japan. 67巻・4号. 1440-1450 (1998)

    • Related Report
      1999 Annual Research Report
  • [Publications] H.Kuroe: "Raman Scattering in the Inorganic Spin-Peierls System α'-Na_<1-8>V_2O_5"Journal of the Physical of Japan. 67巻・7号. 2881-2892 (1998)

    • Related Report
      1999 Annual Research Report
  • [Publications] H.Kuroe: "Spin-Peierls Transition in α'NaV_2O_5 Observed by Raman Scattering"Physica B. 263巻・264号. 803-805 (1999)

    • Related Report
      1999 Annual Research Report
  • [Publications] H.Kuroe: "Raman Scattering in Zn-,Si-and Mg-Doped CuGeO_3"Physica B. 263巻・264号. 825-828 (1999)

    • Related Report
      1999 Annual Research Report
  • [Publications] H.Kuroe: "Folded Phonon Mode Observed by Raman Scattering in Zn-and Si-Doped CuGeO_3"Journal of the Physical of Japan. 68巻・6号. 2046-2056 (1999)

    • Related Report
      1999 Annual Research Report
  • [Publications] 黒江晴彦: "スピン・パイエルス物質CuGeO_3の光散乱"固体物理. 35巻・2号. 105-119 (2000)

    • Related Report
      1999 Annual Research Report
  • [Publications] H.Kuroe: "Raman and Luminescence Spectra in the Spin-Peierls System Cu_<1-x>Ni_xGeO_3"Physica B. (発売予定).

    • Related Report
      1999 Annual Research Report
  • [Publications] T.Sekine: "Spin-Peierls Gap and Two-Magnetic-Excitation Bound and Resonant States in Cu_<1-x>Zn_xGeO_3 and CuGe_<1-y>Si_yO_3" Journal of Physical Society of Japan. 67巻4号. 1440-1450 (1998)

    • Related Report
      1998 Annual Research Report
  • [Publications] H.Kuroe: "Raman Scattering in the Inorganic Spin-Peierls System α′-Na_<1-δ> V_2 O_5" Journal of Physical Society of Japan. 67巻8号. 2881-2892 (1998)

    • Related Report
      1998 Annual Research Report
  • [Publications] H.Kuroe: "Spin-Peierls Transition in α′-NaV_2O_5 observed by Raman Scattering" Physica B. 発表予定.

    • Related Report
      1998 Annual Research Report
  • [Publications] H.Kuroe: "Raman Scattering in Zn,Si-and Mg-Doped CuGeO_3" Physica B. 発表予定.

    • Related Report
      1998 Annual Research Report

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Published: 1998-04-01   Modified: 2020-05-15  

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