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Optical Microscopic Faraday Rotation Study on Magnetization Relaxation in the Spin Systems Having Ordered Structures with Non-trivial Degeneracy

具有非平凡简并有序结构的自旋系统磁化弛豫的光学显微法拉第旋转研究

基本信息

批准号：
03452034
负责人：
IIO Katsunori
金额：
$ 4.35万
依托单位：
TOKYO INSTITUTE OF TECHNOLOGY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1993
项目状态：
已结题

项目摘要

In condensed matter with competing interactions, inhomogeneity in specimens disturbs observation of true feature of dynamic and static properties of their multi-degenerate ordered states. To remove this difficulty, we have developed a new experimental system measuring magnetization and its long time decay on a homogeneous region extracted by means of a microscope. For the term of this research project over three years, the main task was to construct an apparetus equiped with a superconducting magnet for optical access for measuring magneto-optical effects, such as Faraday rotation and optical birefringence and to do that with an optical microscope. The final aim was to link those two systems together. Although the former system has already been operated, the latter is just settled recently.On the other hand, a couple of research programs associated with this study bring about important results. In a mixed compound with Ising -like interaction, Fe_<1-x>MG_xCl_2, long time decay of remanent magnetization due to the random field effect and spin glass behavior could be characterized. Furthermore, as new problems inherent to competing systems, the successive phase transition accompanied with the first order transition in hexagonal layr type MnX_2(X=Br, I)were clarified with respect to magnetic structures of each phase and a mechanism of successive transition. Ferroelectricity was found in the KNICl_3 type lattice with the space group P6_3cm. The latter finding opened a new paradigm in which the physics reflecting coexistence of antiferromagnetism and ferroelectricity is attracted considerable attention. Experimental system with superconducting magnet was succeeded in measuriong the magnetic phase diagram of a triangular lattice antiferromagnet RbMnBr_3 and a layr type magnet with competing interactions NiBr_2. In this way, it takes further effort to fulfilll our project. However the prospect of the present project is rather widely opened.

在具有竞争相互作用的凝聚态中，试样的不均匀性影响了对其多简并有序态动静态特性真实特征的观察。为了克服这一困难，我们开发了一种新的实验系统，可以在显微镜提取的均匀区域上测量磁化强度及其长时间衰减。本课题在三年多的时间里，主要任务是构建一个配备超导磁体的光学接入装置，用于测量法拉第旋转、光学双折射等磁光效应，并使用光学显微镜进行测量。最后的目标是将这两个系统连接在一起。虽然前一种制度已经开始运作，但后一种制度最近才刚刚结算。另一方面，与这项研究相关的几个研究项目带来了重要的结果。在类伊辛相互作用的混合化合物Fe_<1-x>MG_xCl_2中，由于随机场效应和自旋玻璃行为导致的长时间剩余磁化衰减可以被表征。此外，作为竞争体系固有的新问题，明确了六方层型MnX_2（X=Br， I）中伴随一阶相变的连续相变各相的磁性结构和连续相变的机理。在空间群为P6_3cm的KNICl_3型晶格中发现了铁电性。后者的发现开辟了一个新的范式，其中反映反铁磁性和铁电性共存的物理学引起了相当大的关注。利用超导磁体实验系统成功地测量了三角形晶格反铁磁体RbMnBr_3和具有竞争相互作用的层状磁体NiBr_2的磁相图。这样，完成我们的项目需要进一步的努力。然而，目前项目的前景是相当广阔的。