1999 Fiscal Year Final Research Report Summary
DYNAMICS OF LATTICE STRAIN FIELD NEAR PHASE TRANSITION
| Project/Area Number |
09440133
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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 | THE UNIVERSITY OF TOKYO |
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Principal Investigator |
KAKURAI Kazuhisa THE UNIV. OF TOKYO, ISSP, PROF., 物性研究所, 教授 (00204339)
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| Co-Investigator(Kenkyū-buntansha) |
NISHI Masakazu THE UNIV. OF TOKYO, ISSP, RESEARCH ASSOCIATE, 物性研究所, 助手 (90156034)
NAKAJIMA Kenji THE UNIV. OF TOKYO, ISSP, RESEARCH ASSOCIATE, 物性研究所, 助手 (10272535)
FUJII Yasuhiko THE UNIV. OF TOKYO, ISSP, PROF., 物性研究所, 教授 (00013524)
ASO Naofumi THE UNIV. OF TOKYO, ISSP, RESEARCH ASSOCIATE, 物性研究所, 助手 (40313118)
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| Project Period (FY) |
1997 – 1999
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| Keywords | NEUTRON SCATTERING / SPIN ECHO SPECTROSCOPY / PHASE TRANSITION |
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| Research Abstract |
The aim of this project is the development of the thermal neutron spin echo spectroscopy for the detailed study of lattice dynamics near phase transition.
1. For this purpose the newly developed thermal neutron spin echo option on ISSP-PONTA spectrometer has been improved.
(1) Spin echo test experiment using neutron wave length λ=1.609Å has been performed. The use of this wave length pushes the lower limit of the dynamical time range down to 7 picosec, thus covering the dynamical range of 7 to 155 picosec by using both 1.609Å and 2.35Å wave length neutrons.
(2) Spin echo experiment at large Q=2.9ÅィイD1-1ィエD1 has been successfully performed.
(3) Pairs of gradient coils have been designed constructed and tested. These coils create additional neutron spin precession field integral component depending on the neutron flight paths within the divergence of the neutron beam and allow to match the slope of the spin echo line to the slope of the excitation dispersion to be studied (spin echo focussin
… More
g).
2. Spin echo experiment at finite energy transfer and especially the use of above mentioned gradient coils demand the introduction of spin echo simulation program to plan and analyse the experiments.
(1) Spin echo simulation program has been developed and is being tested.
(2) The phonon line width measurement in SrTiO3 has been analysed using the simulation program.
3. Few quasielastic thermal neutron spin echo experiments have been performed.
(1) Slow spin dynamics in 2-D, triangular lattice system CuFeィイD20.95ィエD2AlィイD20.05ィエD2OィイD22ィエD2 has been studied, showing the static nature of the moment at low T in the time scale of 140 picosec.
(2) Larmor spin precession phase shift near the magnetic satellite peak of Ho in transmission geometry has been observed for the first time.
(3) Slow dynamics in Polybutadiene towards its glass transition at large Q=2.9ÅィイD1-1ィエD1 has been studied for the first time. The T-dependence of the dynamics at this large Q is found to be different than that of small Q sofar studied.
4. Possible candidates to study the lattice distortions near phase transition with spin echo spectroscopy have been studied, especially the spin and lattice dynamics in the spin-Peierls system CuGeOィイD23ィエD2 and the charge ordering system NaVィイD22ィエD2OィイD25ィエD2 have been studied. Less
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