1989 Fiscal Year Final Research Report Summary
NMR Study of Magnetic Random Mixture
Project/Area Number |
62540272
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Research Category |
Grant-in-Aid for General Scientific Research (C)
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Allocation Type | Single-year Grants |
Research Field |
物性一般(含極低温・固体物性に対する理論)
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Research Institution | Fukuoka Institute of Technology |
Principal Investigator |
KUBO Hidenori Fukuoka Institute of Technology, Faculty of Engineering, Professor., 工学部, 教授 (10037913)
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Project Period (FY) |
1987 – 1989
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Keywords | Spin glass phase / Oblique antiferromagnetic phase / Random mixture / Competing anisotropies / Competing exchange interactions |
Research Abstract |
In the random mixture with competing magnetic interactions, the new magnetic phases have been observed in the intermediate concentration region. In the present study by the NMR measurements, we have clarified the spin structure of the new phases and the properties of the phase transition with the antiferromagnetic phase. (1) Oblique Antiferromangeic Phase In the random mixture of two antiferromangets with competing anisotropies, there exists the oblique antiferromangetic phase. Proton NMR measurements have been carried out in CsMn_<1-x>Co_xCl_32H_2O. In the oblique antiferromangetic phase, we have pointed out the existence of two domains with the easy axis of pure CsCoCl_32H_2O and CsMnCl_32H_2O. At the transition to the antiferromangetic phase, the nuclear relaxation rate of one of two domains diverses. However, the relaxation rate of the other domain does not show any divergences. This result shows that the phase transition between the antiferromangetic and oblique antiferromagnetic phases is not due to the whole spins. Only one of the two domains shows the phase transition. This is the new type of the phase transition. (2) Spin Glass Phase In the mixture of the competing exchange interactions, the existence of the spin glass phase has been known. NMR measurements are carried out on the mixture Co_<1-x>Mn_xCl_22H_2O. We have shown that the phase transition to the spin glass phase occurs at about 2.5K and in the concentration of about x=0.2 at low temperature. By the proton NMR, in the spin glass phase, the intermediate type of the magnetic structure coexists with the Co- and Mn-type magnetic structures. The further studies are now in progress on the magnetic properties of the phase transition.
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Research Products
(12 results)