Search for New A'_3ABO_6-Type 1D-Antiferromagnets and Research on Their Physical Properties-around Ca_3Co_2O_6

围绕Ca_3Co_2O_6寻找新的A_3ABO_6型一维反铁磁体及其物理性质研究

基本信息

批准号：
11440195
负责人：
KOSUGE Koji
金额：
$ 10.69万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

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.

在这项研究中，我们精确地研究了哪些金属元件可以放入A'_3ABO_6中的A'，A和B位点，该化合物具有K_4CDCL_6型结构，以阐明该结构的一般稳定性条件。因此，研究的目的是通过利用获得的条件并研究其物理特性，搜索新的各种1D磁铁。实验结果如下。使用K_4CDCL_6型结构进行搜索，我们已经成功地合成了这三种新化合物：Ca_3coiro_6，ca_3coruo_6和ca_3corho_6。尤其是，Ca_3corho_6指示具有Ising-Type型铁磁性旋转链的2D-三角晶格抗铁磁体（2D-TLA）的行为，就像CA_3CO_2O_6一样，这两种情况都表明两个Neel温度，T_ <n1>和T_ <n1>和T_ <n2>。在T_ <n1>和T_ <n2>之间的温度状态中，CA_3Corho_6的磁态被发现是部分无序的抗抗铁磁（PDA），这是由中子衍射实验研究的2D-TLA的特征。这是对2D-TLA中PDA状态的首次观察，其中具有ISING型铁磁链，尽管在2D-TLA的情况下，PDA状态几乎不被带有铁磁链。此外，已经发现PD旋转链被随机冷冻在T_N以下，因为铁磁孵化几乎无法向下上下移动。因此，T_N的过渡是从PDA状态到温度降低的自旋玻璃状态，在此下，共存状态以2/3抗磁磁链和1/3的冷冻自旋链实现。为了打破冷冻状态并翻转自旋链，我们发现至少需要非常高的磁场至少需要10吨。对于完全理解低维磁系统的全面研究是必要的。