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Optical Properties of One-Dimensional Charge-Density-Wave Semiconductors under High Pressures

Research Project

Project/Area Number 60460026
Research Category

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

Allocation TypeSingle-year Grants
Research Field 固体物性
Research InstitutionTOHOKU UNIVERSITY

Principal Investigator

KURODA NORITAKA  The Research Institute for Iron, Steel and Other Metals, Assoc.Prof., 金属材料研究所, 助教授 (40005963)

Co-Investigator(Kenkyū-buntansha) NISHITANI Ryusuke  the same as above,Assist.Prof, 金属材料研究所, 助手 (50167566)
SASAKI Yoshiro  the same as above,Assist.Prof, 金属材料研究所, 助手 (90101154)
NISHINA Yuichiro  The Research Institute for Iron, Steel and Other Metals,Prof, 金属材料研究所, 教授 (90005851)
Project Period (FY) 1985 – 1986
Project Status Completed (Fiscal Year 1986)
Budget Amount *help
¥6,700,000 (Direct Cost: ¥6,700,000)
Fiscal Year 1986: ¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1985: ¥4,900,000 (Direct Cost: ¥4,900,000)
KeywordsHalogen-bridged Mixed-Valence Plutinum Complex / Charge Density Wave / Soliton / Diamond Anvil / 顕微分光装置
Research Abstract

We have studied the pressure dependence of the optical absorption spectrum in quasi one-dimensional halogen-bridged <Pt^(II)> - <Pt^(IV)> complexes to clarify the role of the transfer energy between <dz^2> orbitals of Pt ions in determining the Peierls gap, and to search for the excitation of kink solitons which must be born in these doubly degenerate charge density wave systems. The hydrostatic pressure is generated by the use of the diamond anvil apparatus. Since the optical transition across the Peierls gap is allowed only for the electric field directed parallel to the -X- <Pt^(II)> -X- <Pt^(IV)> -X- chain (X = Cl,Br,I), the light source must be linearly polarized. For this purpose, we have developed the technique to seal the linear polarizer into the pressure cell together with a single crystal of the sample. This technique enables us to obtain the linearly polarized absorption spectrum at pressures up to 3 GPa, despite that the radiation is strongly depolarized by the strain of t … More he diamond anvils. The fundamental absorption edge is found to shift towards lower energies with increase in the pressure, the rate being -0.2 - -0.3 eV/GPa in all the materials examined. The rate is about an order of magnitude higher than that of the indirect absorption edge in an ordinary semiconductor. It turns out from this result that the increase in the transfer energy, that is, the kinetic energy causes to decrease the Peierls gap. This fact implies that the application of pressure increases the metallicity of a one-dimensional semiconductor quite efficiently. Besides, a midgap absorption band appears upon the onset of pressure in the Pt-Cl salt. The spectral position remains near the middle of the Peierls gap at any pressure. The absorption intensity increases as an exponential function of the shift of the spectral position. It is concluded from these findings that the states responsible for the midgap absorption band are soliton excitations similar to the kinks in polyacetylene. Less

Report

(1 results)
  • 1986 Final Research Report Summary
  • Research Products

    (10 results)

All Other

All Publications (10 results)

  • [Publications] 黒田規敬: Physical Review B. 35. (1987)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1986 Final Research Report Summary
  • [Publications] 黒田規敬: Physical Review Letters.

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1986 Final Research Report Summary
  • [Publications] 黒田規敬: Journal of the Physical Society of Japan. 55. 581-589 (1986)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1986 Final Research Report Summary
  • [Publications] 酒井政道: Jounal of the Physical Society of Japan. 54. 4081-4084 (1985)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1986 Final Research Report Summary
  • [Publications] 黒田規敬: Journal of the Physical Society of Japan. 54. 1423-1429 (1985)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1986 Final Research Report Summary
  • [Publications] Noritaka Kuroda: "Soliton-to-Band Optical Absorption in a Quasi One-Dimensional <Pt^(II)> - <Pt^(IV)> Mixed-Valence Complex under Hydrostatic Pressures" Physical Review Letters (submitted).

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1986 Final Research Report Summary
  • [Publications] Noritaka Kuroda: "Lattice-Dynamical and Photoelastic Properties of GaSe under High Pressures Studied by Raman scattering and Electronic Susceptibility" Physical Review B. 35. (1987)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1986 Final Research Report Summary
  • [Publications] Noritaka Kuroda: "Supernonlinear Shift of Optical Energy Gaps in InSe and GaSe under Hydrostatic Pressure" Journal of the Physical Society of Japan. 55. 581-589 (1986)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1986 Final Research Report Summary
  • [Publications] Masamichi Sakai: "Raman Scattering and X-ray Diffraction Studies on Phase Transitions in <ZnCl_2> under Hydrostatic Pressure" Journal of the Physical Society of Japan. 54. 4081-4084 (1985)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1986 Final Research Report Summary
  • [Publications] Noritaka Kuroda: "Anharmonicity of Low Frequency Lattice Vibrations in Red- <HgI_2> " Journal of the Physical Society of Japan. 54. 1423-1429 (1985)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1986 Final Research Report Summary

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Published: 1987-03-31   Modified: 2016-04-21  

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