1990 Fiscal Year Final Research Report Summary
Neutron Scattering Study of Weak Antiferromagnets
| Project/Area Number |
01540261
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
固体物性
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| Research Institution | Tohoku University |
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Principal Investigator |
YAMAGUCHI Yasuo Institute for Material Research, Prof. Tohoku University, 金属材料研究所, 教授 (80005917)
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| Co-Investigator(Kenkyū-buntansha) |
TOMIYOSHI Shoichi Institute for Materials Research, Researcher Tohoku University, 金属材料研究所, 助手 (50005922)
OHASHI Masayoshi Institute for Materials Research. Researcher Tohoku University, 金属材料研究所, 助手 (00005894)
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| Project Period (FY) |
1989 – 1990
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| Keywords | Neutron Scattering / Metallic Magnets |
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| Research Abstract |
One of recent progresses in research of magnetism is due to development of SCR theory which deals spin fluctuation in metallic magnets. Now the theory can explain quantitatively the properties of weak ferromagnets of MnSi and Ni_3Al etc. In the present stage of the theory, the main theme goes to the weak antiferromagnets. Qualitative calculations have been done on the weak antiferromagnets, and the corresponding experiments are earnestly desired to do. On the other hand experiments shows the properties of the weak antiferromagnets being greatly different from those of ferromagnets, for example the slope of spin of spin wave in metallic antiferromagnets is very steep reflecting the electron band structure of them.
We try to study on the weak antiferromagnets which are simple enough to compare with the SCR theory. In the present investigation we picked up FeSb and Mn_3Pt. In the case of FeSb, we could make a single crystal of Fe_<1027>Sb on which we made neutron scattering measurements and found slope of the spin wave being very steep. Mn_3Pt is a metallic antiferromagnet with TN=480 K taking collinear spin structure, and transforms to a triangular spin structure at Tt=415 K. We also made single crystals of Mn_3Pt, and studied the magnetic structure and the spin wave excitations. Cubic symmetry of the magnetostriction and isotropic nature of the spin wave dispersion suggest the magnetic structures of Mn_3Pt to be multi-Q structures of cubic symmetry for high and also low temperature phases instead of the uni-axial structure proposed in the previous reports. The slope of the spin wave dispersion of Mn_3Pt is about two times steeper compared with the prediction by molecular field theory.
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