2000 Fiscal Year Final Research Report Summary
Search for New A'_3ABO_6-Type 1D-Antiferromagnets and Research on Their Physical Properties-around Ca_3Co_2O_6
| Project/Area Number |
11440195
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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 |
Inorganic chemistry
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
KOSUGE Koji Kyoto Univ., Graduate School of Sci., Prof., 大学院・理学研究科, 教授 (00025371)
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| Co-Investigator(Kenkyū-buntansha) |
KATO Masaki Kyoto Univ., Graduate School of Sci., Instructor, 大学院・理学研究科, 助手 (90271006)
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| Project Period (FY) |
1999 – 2000
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| Keywords | 2D-Triangular-Lattice Antiferromagnet / 1D-Ferromagnetic Chain / Transition-Metal Compound / Magnetic Frustration / Neutron Diffraction / High-Field Magnetization |
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| Research Abstract |
In this study, we have precisely investigated which metal-elements can be put into the A', A and B sites in the A'_3ABO_6 compounds with K_4CdCl_6-type structure in order to clarify the general stability condition of this structure. Thus, the purpose of the study is to search the new various 1D-magnets with this structure by utilizing the obtained conditions and to investigate their physical properties. Experimental results are as follows.
Searching the new compounds with the K_4CdCl_6-type structure, we have been succeeded in synthesizing these three new compounds : Ca_3CoIrO_6, Ca_3CoRuO_6 and Ca_3CoRhO_6. Especially, Ca_3CoRhO_6 indicates the behaviors of the 2D-triangular lattice antiferromagnets (2D-TLA) with the Ising-type ferromagnetic spin chains just as the case with Ca_3Co_2O_6, both of which indicate two Neel temperature, T_<N1> and T_<N2>. In the temperature regime between T_<N1> and T_<N2>, the magnetic state of Ca_3CoRhO_6 has been found to be the partially disordered antiferromagnetic (PDA) one, which is characteristic to the case of the 2D-TLA, investigated by neutron diffraction experiments. This is the first observation of the PDA state in the 2D-TLA with Ising-type ferromagnetic chains, although the PDA state has been hardly thought to be realized in the 2D-TLA case with the ferromagnetic chains. Furthermore, the PD spin chains have been found to be frozen randomly below T_N, because the ferromagnetic hatchings can hardly flip up to down and down to up. Consequently, the transition at T_N is that from the PDA state to the spin glass state with decreasing temperature, below which the coexistence state is realized of 2/3 antiferromagnetic chains and 1/3 frozen spin chains. In order to break the frozen state and to flip the spin chain, we found to need very high magnetic fields more than several 10 T at least. Further investigations are necessary for fully understanding of the low dimensional magnetic systems.
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