1998 Fiscal Year Final Research Report Summary
Study of diffusion phenomena of spin particles by a new technique of high resolution neutron spectroscopy
| Project/Area Number |
09440143
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
固体物性Ⅱ(磁性・金属・低温)
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| Research Institution | HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION |
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Principal Investigator |
FURUSAKA Michihiro HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION, Institute of Materials Structure Science Associate Professor, 物質構造科学研究所, 助教授 (60156966)
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| Co-Investigator(Kenkyū-buntansha) |
IKEDA Hironobu HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION.Institute of Materials Structure S, 物質構造科学研究所, 教授 (90013523)
ITOH Shinichi HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION, Institute of Materials Structure, 物質構造科学研究所, 助手 (00221771)
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| Project Period (FY) |
1997 – 1998
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| Keywords | neutron scattering / pulsed neutron / fractal / percolation / self correlation function / high energy resolution / spin diffusion |
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| Research Abstract |
It was difficult to observe the diffusion of single particles on a medium by scattering techniques. Unsolved subjects among such phenomena are anomalous diffusion on a fractal lattice, the long time tail in spin diffusion on a low-dimensional lattice, and so on. The wavenumber-integration of the scattering function obtained by inelastic neutron scattering is equal to the Fourier transform of the self correlation function. This quantity was hardly obtained by a conventional neutron scattering. However, recent developments on pulsed-neutron spectroscopy enables us to observe the self correlation function in the terms of the energy spectrum, and the above listed unsolved subjects can be elucidated. The self-correlation function decays exponentially in the spin diffusion on a homogeneous medium. On a percolating network, the diffusion is anomalous and the self correlation function shows a power law. We previously observed the energy spectrum with a power law in the spin diffusion in a two-dimensional percolating magnet, Rb_2Co_<0.6>Mg_<0.4>F_4, In order to make sure that the line shape of only the near-percolating system is anomalous and that of a corresponding pure compound Rb_2CoF_4 takes the form of a Lorentzian. The observed energy spectrum was well described by a Lorentzian. We also tried to observe the long time tall in a one-dimensional magnet, CsMnBr_3. We observed energy spectrum with a power law at very small energy region. Further, we performed a high energy resolution measurement on a three-dimensional percolating magnet, RbMn_<0.39>Mg_<0.61>F_3, and firstly observed the crossover from spin wave excitations at long wavelength limit to a fracton excitations with decreasing the wavelength.
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