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1999 Fiscal Year Final Research Report Summary

Thermal induced metal-insulator transition in the titanium oxides single crystals with a high melting point

Research Project

Project/Area Number 10440110
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 InstitutionHiroshima University

Principal Investigator

IGA Fumitoshi  Hiroshima University, Graduate School of Advanced Sciences of Matter, Associate Professor, 大学院・先端物質科学研究科, 助教授 (60192473)

Co-Investigator(Kenkyū-buntansha) UMEO Kazunori  Hiroshima University, Graduate School of Advancred Sciences of Matter, Research Associate, 大学院・先端物質科学研究科, 助手 (10223596)
TAKABATAKE Toshiro  Hiroshima University, Graduate School of Advancred Sciences of Matter, Professor, 大学院・先端物質科学研究科, 教授 (40171540)
Project Period (FY) 1998 – 1999
KeywordsMott transiton / metal-insulator transition / orbital order / spin-charge separation / pressure effect / electrical resistivity / photoemission sepectroscopy / Perovskite-type oxide
Research Abstract

We have studied the mechanism of a metal-insulator (M-I) transition by the magnetic, transport and thermal measurements of YィイD21-xィエD2CaィイD2xィエD2TiOィイD23ィエD2 (x=0.3〜0.4) which exhibits inverse-Mott transition from a metallic state at low temperatures to a semiconducting one at high temperatures.
1. Crystal growth and characterization: We have developed the method of growth for YィイD21-xィエD2CaィイD2xィエD2TiOィイD23ィエD2 single crystals by using an image furnace. Oxygen contents of samples were determined by thermo-gravimetric analysis(TGA) . The results of TGA was used to obtain the best conditions for annealing under flowing oxygen.
2. High-resolution photoemission spectroscopy : We have observed a clear M-I transition in the temperature-dependent photoemission spectra for x=0.39 consistent with transport measurements.
3. Spin-charge separation : In a M-1 transition region, the significant difference in temperature dependences exist between magnetic .susceptibility and electrical resistivity. For a sample in the ferromagnetic region (x=0.05), we have found the stability of an orbital-ordered state a-s for x=0 by spin-polarized neutron diffraction.
4. Future plans : Correlations among the charge , s pin and orbital in YィイD21-xィエD2CaィイD2xィエD2TiOィイD23ィエD2 will be studied by the X-ray diffraction using synchrotron radiation and the spin-polarized neutron diffraction.

  • Research Products

    (10 results)

All Other

All Publications (10 results)

  • [Publications] M.Arita: "Temperature-Dependent High-Resolulio Photoemission Study of Yl_<1-X>Ca_XTiO_3"Jpn.I.Appl.Phys.. 38. 206-208 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] M.Tsubota: "Temperature-Dependent High-Resolulio Photoemission Study of Yl_<1-X>Ca_XTiO_3(x<0.1)"Physica B. (in press). (2000)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] M.Arita: "High-Resolution Temperature-Dependent Photoemission study of Metal-Insulator Transition in Yl_<1-X>Ca_XTiO_3"Physica B. (in press). (2000)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] F.Iga: "Effects of High Pressure and High-Magnetic Field on the Energy Gap in a Konao Semiconductor YbB_<12>"Jpn.J.Appl.Phys.. Series11. 88-90 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] T.Susaki: "Temperature-Dependent High-Resolution-Photoemission Study of YbB_<12>"Phys.Rev.Lett.. 82. 992-995 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] M. Arita et al.: "Temperature-Dependent High-Resolution Photoemission Study of YィイD21-xィエD2CaィイD2xィエD2TiOィイD23ィエD2"Japanese Journal of Applied Physics. 38, suppl. 38-1. 206-208 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] M. Tsubota et al.: "Low-Field Magnetic Anisotropy in Mott-Insulating Ferromagnet YィイD21-xィエD2CaィイD2xィエD2TiOィイD23ィエD2(x<0.1)"Physica B. (in press). (2000)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] M. Arita et al.: "High-Resolution Temperature-Dependent Photoemission Study of Metal-Insulator Transition in YィイD21-xィエD2CaィイD2xィエD2TiOィイD23ィエD2"Physica B. (in press). (2000)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] F. Iga et al.: "Effects of High Pressure and High-Magnetic Field on the Energy Gap in a Kondo Semiconductor YbBィイD212ィエD2"Japanese Journal of Applied Physics. series 11. 88-90 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] T. Susaki et al.: "Temperature-Dependent High-Resolution Photoemission Study of the Kondo Insulator YbBィイD212ィエD2"Physical Review Letters. 82,5. 992-995 (1999)

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

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Published: 2001-10-23  

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