1997 Fiscal Year Final Research Report Summary
Neutron Scattering Study on the Spin Structure and Spin Dynamics of Organic Magnetic Materials
| Project/Area Number |
08454099
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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 | Ehime University |
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Principal Investigator |
TOMIYOSHI Shoichi Ehime University Department of Materials Science and Engineering, Professor, 工学部, 教授 (50005922)
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| Co-Investigator(Kenkyū-buntansha) |
KONISHI Kensuke Ehime University Department of Physics, Research Assistant, 理学部, 助手 (00263921)
AZUMA Nagao Ehime University, Department of Chemistry, Professor, 理学部, 教授 (00093914)
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| Project Period (FY) |
1996 – 1997
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| Keywords | Organic Magnetic materials / Neutron Diffraction / Spin Structure / TPV / Molecular Mmagnetism |
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| Research Abstract |
Magnetic properties of organic radical compounds are very attractive because the magnetic moment arises from an unpaired 2p electron in the molecular orbitals. However the ordered state in these organic magnetic materials is not well understood, especially spin structure study is not enough. In order to undersand the unique nature of organic magnetic materials we investigated by neutron diffraction the spin structure of an antiferromagnet PTV which has a high Neel temperature of 1.78K.However, because of the difficulties due to its low spin density, and very high neuron background arising from hydrogen atoms consisting the molecule, the observation of the magnetic Bragg reflections is not easy and until now the observation of which has been limited to only (011) reflection. So in the present work we tried to reduce the background by using deuterated TPV crystal which is 24mg in weight and has fairly good mosaic width. By the measurements of X-ray and magnetic susceptibility the deutera
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ted crystal was found to have almost the same crystallographic and magnetic properties as that of usual TPV crystals. Neutron diffraction was measured using a triple axis spectrometer of TOPAN of JRR-3M reactor.
The neutron back ground was fairly reduced by replacing hydrogen with deuteron. And many new magnetic reflections were observed by using deuterated TPV crystal. We analyzed the observed data using several spin structure models with various spin density distributions and we found as the most probable spin structure model of TPV that the antiferromagnetic spin chain extends toward the c direction, keeping antiphase coupling between the neighboring chains in the b-c plane and in-phase coupling between the neighboring chains in the a-c plane, and the spin density in a molecule distributes mainly on four nitrogen atoms in the verdazyl ring. This charge density destribution is roughly consistent with that deduced from the magnetic resonance data. At present the agreement between observed and calculated neutron data is not good due to poor counting statistics, but in near future neuron diffraction data will give clear spin density in organic magnetic materials in their ordered state. Less
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Research Products
(10 results)
