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PHASE TRANSITIONS AND EXCITATIONS IN FRACTAL MAGNETS

Research Project

Project/Area Number 03402009
Research Category

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

Allocation TypeSingle-year Grants
Research Field 物性一般(含極低温・固体物性に対する理論)
Research InstitutionNATIONAL LABORATORY FOR HIGH ENERGY PHYSICS

Principal Investigator

IKEDA Hironobu  NATIONAL LABORATORY FOR HIGH ENERGY PHYSICS, BSF, PROF., ブースター利用施設, 教授 (90013523)

Co-Investigator(Kenkyū-buntansha) ARAI Matatoshi  NATIONAL LABORATORY FOR HIGH ENERGY PHYSICS, BSF, ASSOC.PROF., 理学部, 助教授 (30175955)
FURUSAKA Michihiro  NATIONAL LABORATORY FOR HIGH ENERGY PHYSICS, BSF, ASSOC.PROF., ブースター利用施設, 助教授 (60156966)
IKEDA Susumu  NATIONAL LABORATORY FOR HIGH ENERGY PHYSICS, BSF, ASSOC.PROF., ブースター利用施設, 助教授 (80132679)
Project Period (FY) 1991 – 1993
Project Status Completed (Fiscal Year 1993)
Budget Amount *help
¥29,900,000 (Direct Cost: ¥29,900,000)
Fiscal Year 1993: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 1992: ¥4,800,000 (Direct Cost: ¥4,800,000)
Fiscal Year 1991: ¥23,500,000 (Direct Cost: ¥23,500,000)
KeywordsPERCOLATION / FRACTAL / FRACTON / FRACTAL DIMENSION / NEUTRON SCATTERING / ANOMALOUS DIFFUSION / DILUTE MAGNET / パ-コレ-ション / フラ・クタル / 相転移 / 磁気励起
Research Abstract

It is generally accepted that the atomic connectivity of a percolating cluster takes the form of a fractal. The theory of percolation was formulated by many authors and can now be used to interpret an exceptionally wide variety of physical and chemical phenomena, such as the gelation process, transport in amorphous materials, and hoppoing conduction in a doped semiconductor. The concept of fractals has contributed significantly to the understanding of percolation. The simplest ideal percolating networks are realized by substitutionaly diluting the magnetic systems by non-magnetic atoms. At a critical magnetic concentration (c_p), a single infinite cluster (a percolating network) spans the full space ; with a further decreasing concentration of magnetic atoms, the system splits into an assembly of only finite clusters. The percolating networks exhibit a self-similarity, and can be characterized by a non-integer mass dimension, i. e., a fractal dimension D_f. In a square lattice, it has been numerically estimated that the D_f of the percolating network is 1.896, i.e. D_f is less than the Euclidian dimension, D.As is well established, neutron scattering is a powerful tool to investigate the static and dynamical aspects of magnetic systems. By observing the scattered scattering function that is the space-time Fourier transform of the spin pair-correlation function, we can obtain the detailed information concerning the structural and dynamical properties of these systems. In the present research, we successfully performed neutron scattering experiments in two-and three-dimensional percolating antiferromagnets ; a direct observation of the self-similarity of the magnetic order in a percolating cluster, investigations of the magnetic excitations in percolating antiferromagnets with Ising symmetry, an observation of fractons in a percolating Heisenberg antiferromagnet and an observation of anomalous spin diffusion in a percolating Heisenberg ant

Report

(4 results)
  • 1993 Annual Research Report   Final Research Report Summary
  • 1992 Annual Research Report
  • 1991 Annual Research Report
  • Research Products

    (28 results)

All Other

All Publications (28 results)

  • [Publications] 高橋美和子: "Crossover from propagating spin waves to localized Ising-cluster excitations in diluted Heisenberg antiferromagnets" Phys.Rev.B. 47. 9132-9135 (1993)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] 太田仁: "Electron paramagnetic resonance of CsCo_2Mg_<1-x>Cl_3 and the determination of exchange interactions" J.Phys.Soc.Jpn.62. 2481-2489 (1993)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] 池田宏信: "Self-similarity of magnetic order in two-dimensional percolating antiferromagnets" J.Phys.Soc.Jpn.62. 3832-3836 (1993)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] 小嶋健児: "Spin dynamics in a site diluted finite spin cluster system probed by positive muons" Hyperflne Interactions. 78. 429-433 (1993)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] 矢崎昭: "Neutron paramagnetic scattering from antiferromagnetic RbMnF_3 and Mn_3Pt using time of flight technique" J.Phys.Soc.Jpn.63(印刷中). (1994)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] 岩佐和晃: "Pressure-induced magnetic structure in layered antiferromagnets Rb_2MnF_4 and Cs_2MuF_4" J.Phys.Soc.Jpn.63(印刷中). (1994)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] MIWAKO TAKAHASHI: "CROSSOVER FROM PROPAGATING SPIN WAVES TO LOCALIZED ISING-CLUSTER EXCITATIONS IN DIL UTED HEISENBERG ANTIFERROMAGNETS" PHYS.REV.B. 47. 9132-9135 (1993)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] HITOSHI OHTA: "ELECTRON PARAMAGNETIC RESONANCE OF CsCo_xMg_<1-X>Cl_3 AND DETERMINATION OF EXCHANGE INTERACTIONS" J.PHYS.SOC.JPN. 62. 2481-2489 (1993)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] HIRONOBU IKEDA: "SELF-SIMIL ARITY OF MAGNETIC ORDER IN TWO-DIMENSIONAL PERCOLATING ANTIFERROMAGNETS" J.PHYS.SOC.JPN.62. 3832-3836 (1993)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] KENJI KOJIMA: "SPIN DYNAMICS IN A SITE DILUTED FINITE SPIN CLUSTER SYSTEM PROBED BY POSITIVE MUONS" HYPERFINE INTERACTIONS. 78. 429-433 (1993)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] AKIRA YAZAKI: "NEUTRON PARAMAGNETIC SCATTERING FROM ANTIFERROMAGNETIC RbMnF_3 AND Mn_3Pt USING TIME OF FLIGHT TECHNIQUE" J.PHYS.SOC.JPN.63 (IN PRESS). (1994)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] KAZUAKI IWASA: "PRESSURE-INDUCED MAGNETIC STRUCTURE IN LAYERED ANTIFERROMAGNETS Rb_2MnF_4 AND Cs_2MnF_4" J.PHYS.SOC.JPN.63 (IN PRESS). (1994)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] 高橋,美和子: "Crossover from propagating spin waves to localized lsing-cruster excitations in diluted Heisenberg antiferromagnets" Phys.Rev.B. 47. 9132-9135 (1993)

    • Related Report
      1993 Annual Research Report
  • [Publications] 太田,仁: "Electron paramagnetic resonance of CsCo_xMg_<1-x>Cl_3 and the determination of exchange interactions" J.Phys.Soc.Jpn.62. 2481-2489 (1993)

    • Related Report
      1993 Annual Research Report
  • [Publications] 池田,宏信: "Self-simillarity of magnetic order in two-dimensional percolating antiferromagnets" J.Phys.Soc.Jpn.62. 3832-3836 (1993)

    • Related Report
      1993 Annual Research Report
  • [Publications] 小嶋,健二: "Spin dynamics in a site diluted finite spin clustervsystem probed by positive muons" Hyperfine Interactions. 78. 429-433 (1993)

    • Related Report
      1993 Annual Research Report
  • [Publications] 矢崎,昭: "Neutron paramagnetic scattering from antiferromagnetic RbMnF_3 and Mn_3Pt using time of flight technique" J.Phys.Soc.Jpn.63 (印刷中). (1994)

    • Related Report
      1993 Annual Research Report
  • [Publications] 岩佐,和晃: "Pressure-induced magnetic structure in layered antiferromagnets Rb_2MnF_4 and Cs_2MnF_421GC06:J.Phys.Soc.Jpn." 63(印刷中). (1994)

    • Related Report
      1993 Annual Research Report
  • [Publications] 本河 光博: "Electron Paramagnetic Resonance of Co:Rb_2 Mg F_4 and Anomalous g-Value of Paired Spin System" J.Phys.Soc.Jpn.61. 322-328 (1992)

    • Related Report
      1992 Annual Research Report
  • [Publications] 池田 宏信: "Kinetecs of Ordering in Percolation Magnet" Alp Conf.Proc. 256. 433-440 (1992)

    • Related Report
      1992 Annual Research Report
  • [Publications] 池田 宏信: "Coexistence of Ising cluster excitations and intracluster excitations in dilu ted Ising magnets" Rhys.Rer.B. 45. 7484-7486 (1992)

    • Related Report
      1992 Annual Research Report
  • [Publications] 本河 光博: "EPR of Co^<2+> in Rb_2 Mg F_4 and anomalous g-valqes of pair and trimer spin systens" J.Mag.Mag.Mater.104/107. 947-948 (1992)

    • Related Report
      1992 Annual Research Report
  • [Publications] 高橋 美和子: "Crossover from propagating spin-waves to localized Ising-cluster excitations in diluted Heisenberg antiferromagnets" Phys.Rev.B. 47. (1993)

    • Related Report
      1992 Annual Research Report
  • [Publications] M.Takahashi (高橋 美和子): "Magnetic excitations in isolated clusters of a diluted Heisenberg magnet RbMr_<0.15>Mg_<0.85>F_3" J.Phys.Soc.Jpn.60. 387-388 (1991)

    • Related Report
      1991 Annual Research Report
  • [Publications] S.Ito (伊藤 晋一): "Dynamical process of disordering in a percolation magnet under random fields" J.phys.Soc.Jpn.60. 3238-3241 (1991)

    • Related Report
      1991 Annual Research Report
  • [Publications] M.Motokawa (本河 光博): "Electron paramagnetic resonance of Co:Rb_2MgF_4and anomalous gーvalue of paired spin System" J.Phys.Soc.Jpn.61. 322-328 (1992)

    • Related Report
      1991 Annual Research Report
  • [Publications] H.Ikeda (池田 宏信): "Coexistence of Ising cluster excitations and intracluster excitations in diluted Ising magnets" Physical Review B. 45. (1992)

    • Related Report
      1991 Annual Research Report
  • [Publications] H.Ikeda (池田 宏信): "Kinetics of ordering in the percolation magnet" Proc.International Conf.on Slow Dynamics in Condensed Matter,America Institute of Physics. (1992)

    • Related Report
      1991 Annual Research Report

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Published: 1991-04-01   Modified: 2016-04-21  

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