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FORMATION OF AN EXCITONIC FERROMAGNETIC MOMENT IN THE LOW DENSITY-CARRIER BORIDES

Research Project

Project/Area Number 12640353
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 InstitutionHIROSHIMA UNIVERSITY

Principal Investigator

IGA Fumitoshi  Hiroshima University, Graduated School of Advanced Sciences of Matter, Dept. of Quantum Matter, Associate Prof., 大学院・先端物質科学研究科, 助教授 (60192473)

Co-Investigator(Kenkyū-buntansha) UMEO Kazunori  Hiroshima University, Graduated School of Advanced Sciences of Matter, Dept. of Quantum Matter, Research Associate, 大学院・先端物質科学研究科, 助手 (10223596)
TAKABATAKE Toshiro  Hiroshima University, Graduated School of Advanced Sciences of Matter, Dept. of Quantum Matter, Prof., 大学院・先端物質科学研究科, 教授 (40171540)
Project Period (FY) 2000 – 2001
Project Status Completed (Fiscal Year 2001)
Budget Amount *help
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2001: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2000: ¥2,500,000 (Direct Cost: ¥2,500,000)
KeywordsLow density-carrier system / Borides / ferromagnet / Lattice defect / Heat treatment / Excitonic Insulator / Muon Spin Relaxation / Internal field / 低密度キャリア / 硼化物 / 単結晶 / 電気抵抗 / バンド計算 / μSR
Research Abstract

We have found that Yb_<1-x>La_xB_6 (x<0.006) has a very similar electronic structure as that of the excitonic ferromagnet Ca_<1-x>La_xB_6 and that this alloy system shows ferromagnetic transition at Curie point Tc = 150-200 K by manetization and muon spin-relaxation (μSR).
1. Single crystal growth : YbB_6 single-crystal samples were grown by a floating-zone method using an image furnace equipped with four-xenon lamps. In order to eliminate impurity phase YbB_<50> from the crystals of YbB_6, a nominal composition of Yb_<1.1>B_6 was chosen for sintered polycrystalline rods for the single-crystal growth. This as-cast sample shows diamagnetism. After heat treatment to introduce Yb-defect we have found that large paramagnetic moment was formed.
2. polycrystalline sample : Sintered polycrystalline sample has a sponge-like surface that has been sintered in vacuum by using a radi-frequency induction-furnace. The high-resolution x-ray diffraction analysis and EPMA revealed that both polycrystals and single crystals have no impurities of FeB and Fe_2B except for a small amount of paramagnetic YbB_4 (【less than or equal】0.001 at%). After acid etching treatment, polycrystalline sample shows ferromagnetism with Tc = 150-200 K. In the next research, we will study the surface effect of this sintered sample for magnetic property.
3. μSR : we have performed μ^+SR measurement for both single crystals and polycrystals from 300 K down to 10 K. Relaxation spectra shows typical paramagnetic pattern. Internal fields deduced from relaxation rate are 0.2 mT at room temperature, and do not change down to 150 K. On cooling further, the internal field increases strongly and reaches a value of 0.6 mT at 10 K. this temperature depence is very similar to that of the magnetic susceptibility.

Report

(3 results)
  • 2001 Annual Research Report   Final Research Report Summary
  • 2000 Annual Research Report
  • Research Products

    (22 results)

All Other

All Publications (22 results)

  • [Publications] F.Iga: "Thermoelectric properties of the Kondo semiconductor : Yb1-xLuxB12"Journal of Magnetism and Magnetic Materials. 226-230. 85-86 (2001)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] M.Udagawa: "Raman scattering investigation of high temperature ferromagnetic crystals"J. Phys. Soc. Jpn.. 71(In press). (2002)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] M.Sera: "Ce site substitution effects on the multipolar interactions in CeB6"J. Phys. Soc. Jpn.. 71(in press). (2002)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] H.Takagiwa: "Magnetic Properties in Phase IV of Ce0.7La0.3B6 and Ce0.8Nd0.2B6 probed by Muon Spin Relaxation"J. Phys. Soc. Jpn.. 71. 31-34 (2002)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] T.Susaki: "Photoemission study of substitution effects in the Kondo insulator YbB12"J. Phys. Soc. Jpn.. 70. 756-761 (2001)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] H.Okamura: "Optical conductivity of Yb1-xLuxB12:Energy gap and mid-infrared peak in diluted Kondo semiconductors"Phys. Rev. B. 62・20. 13265-13269 (2000)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] F. Iga: "Thermoelectric properties of the Kondo semiconductor : Yb_<1-x>Lu_xB_<12>"Journal of Magnetism and Magnetic Materials. 226-230. 85-86 (2001)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] U. Udagawa: "Raman scattering investigation of high temperature ferromagnetic crystals"J. Phys. Soc. Jpn.. 71 (IN PRESS). (2002)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] S. Sera: "Ce site substitution effects on tne multipolar interactions in CeB_6"J. Phys. Soc. Jpn.. 71 (IN PRESS). (2002)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] H. Takagiwa: "Magnetic Properties in Phase IV of Ce_<0.7>La_<0.3>B_6 and Ce_<0.8>Nd_<0.2>B_6 probed by Muon Spin Relaxation"J. Phys. Soc. Jpn.. 71. 31-34 (2002)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] T. Susaki: "Photoemission study of substitution effects in the Kondo insulator YbB_<12>"J. Phys. Soc. Jpn.. 70. 756-761 (2001)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] H. Okamura: "Optical conductivity of Yb_<1-x>Lu_xB_<12> : Energy gap and mid-infrared peak in diluted Kondo semiconductors"Phys. Rev. B. 62-20. 13265-13269 (2000)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] F.Iga: "Thermoelectic properties of the Kondo semiconductor : Yb1-xLuxB12"Journal of Magnetism and Magnetic Materials. 226-230. 85-86 (2001)

    • Related Report
      2001 Annual Research Report
  • [Publications] M.Udagawa: "Raman scattering investigation of high temperature ferromagnetic crystals"J.Phys.Soc.Jpn.. 71(in Press). (2002)

    • Related Report
      2001 Annual Research Report
  • [Publications] M.Sera: "Ce site substitution effects on the multipolar interactions in CeB6"J.Phys.Soc.Jpn.. 71(in Press). (2002)

    • Related Report
      2001 Annual Research Report
  • [Publications] H.Takagiwa: "Magnetic Properties in Phase IV of Ce0.7La0.3B6 and Ce0.8Nd0・2B6 probed by Muon Spin Relaxation"J.Phys.Soc.Jpn.. 71. 31-34 (2002)

    • Related Report
      2001 Annual Research Report
  • [Publications] T.Susaki: "Photoemission study of substitution effects in the Kondo insulator YbB12"J.Phys.Soc.Jpn.. 70. 756-761 (2001)

    • Related Report
      2001 Annual Research Report
  • [Publications] M-S.Kim: "Transport and magnetic properties of a low-density carrier system SmBiPt"J.Phys.Soc.Jpn.. 71. 3650-3653 (2001)

    • Related Report
      2001 Annual Research Report
  • [Publications] H.Okamura: "Optical conductivity of Yb_<1-x>Lu_xB_<12> : Energy gap and mid-infrared peak in diluted Konso semiconductors"Phys.Rev.B. 62,20. 13265-13269 (2000)

    • Related Report
      2000 Annual Research Report
  • [Publications] S.Hiura: "High-field magnetization and magnrtoresistance of single crystal Yb_<1-x>Lu_xB_<12>(x【less than or equal】1/4)"Physica B. 281&282. 271-273 (2000)

    • Related Report
      2000 Annual Research Report
  • [Publications] M.H.Jung: "Anisotropic Transport and Magnetic Properties and Magnetic-Polaron-like behavior in CeTe_<2-x>"J.Phys.Soc.Japan. 69,3. 937-944 (2000)

    • Related Report
      2000 Annual Research Report
  • [Publications] T.Susaki: "Photoemission study of Kondo insulator YbB_<12>"Physica B. 281&282. 282-283 (2000)

    • Related Report
      2000 Annual Research Report

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Published: 2000-04-01   Modified: 2020-05-15  

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