2002 Fiscal Year Final Research Report Summary
A Study of Slow Dynamics in Spin-Glasses by Means of Time-Resolved Neutron Scattering Measurements
| Project/Area Number |
12440106
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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 | Tokyo University of Science |
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Principal Investigator |
KIYOICHIRO Motoya Tokyo University of Science, Faculty of Science and Technology, Professor, 理工学部, 教授 (60114683)
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| Co-Investigator(Kenkyū-buntansha) |
KIKUCHI Jun Tokyo University of Science, Faculty of Science and Technology, Research Associate, 理工学部, 助手 (90297614)
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| Project Period (FY) |
2000 – 2002
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| Keywords | spin-glass / slow dynamics / neutron scattering / small angle scattering / time-resolved measurement |
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| Research Abstract |
The problem of slow dynamics, or long time relaxation phenomena, has long been a central issue of spin-glasses. However, the experimental studies on slow dynamics have been limited to macroscopic measurements and their phenomenalistic analyses. Based on the previous neutron scattering studies, in which we showed that the magnetic clusters play an important role for the reentrant spin-glass (RSG) transition, we speculate that the mechanism of slow dynamics in concentrated spin-glasses might be closely related to the time evolution of magnetic clusters which can directly be detected by small-angle neutron scattering (SANS) experiment. In this work, we have directly confirmed this conjecture
We have made time-resolved SANS measurements on concentrated spin glass alloys, Fe_65 (Ni_0.866Mn_0.134)_35, Cu_2(Mn_0.70Ti0.30) Al and Fe_0.70Al_0.30 of which characteristics in the stationary state have already been clarified in the previous studies. For all samples slow dynamics has been detected in RSG phase after cooled from the ferromagnetic phase as a time variation of SANS patterns. For Fe_0.70Al_0.30, SANS pattern is well traced by a Lorentzian (LOR) function. Therefore it can be characterized by two parameters, the width and the amplitude of LOR which describe the average size and number of magnetic clusters, respectively. Time-resolved SANS measurements under various temperature and magnetic field have been made. Thus, a microscopic picture of slow dynamics in concentrated spin-glasses has been observed as a time evolution of magnetic clusters
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