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Investigation of magneto-electric optical effect

磁电光学效应研究

基本信息

批准号：
15340112
负责人：
TOKURA Yoshinori
金额：
$ 9.92万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15340112/
关键词：
magneto-electric optical effect magneto-chiral effect breakdown of time reversal and space inversion symmetry x-ray nonreciprocal directional dichroism troidal moment GaFeO3 Fe3O4 スピン軌道相互作用カイラリテイー

项目摘要

We have investigated the new magneto-optical effects termed "magneto-electric optical effect" and "magneto-chiral effect". In these optical effects, the optical response of the depolarized light depends on the direction of the propagator vector. We studied the optical features in the single crystals of the ferrimagnet, GaFeO3, and spinel-type Fe3O4 in order to clarify the mechanism of the magneto-electric optical effect and magneto-chiral one. GaFeO3 has spontaneous magnetization and electric polarization at low temperatures, indicating the breakdown of the space inversion symmetry and the time reversal one, while Fe3O4 has local space inversion symmetry.The magneto-electric optical effect, i.e., the change of optical absorption upon the reversal of the light propagation direction, has been investigated for the polar ferrimagnet GaFeO3 in the energy region of 1.0-2.5 eV. Moreover, we have found a novel magneto-optical effect, termed x-ray nonreciprocal directional dichroism, that the x-ray absorption at around the K edge of an Fe ion depends on whether the x-ray propagation vector is parallel or antiparallel to the outer production of the magnetization and electric-polarization vectors in GaFeO3. These optical responses show the obvious dependence on the electric polarization and magnetization, suggesting the relationship between these optical effects and the toroidal moment. The x-ray nonreciprocal directional dichroism spectroscopy as demonstrated here can be a useful tool to prove the local magnetism in noncentroysymmetric systems such as magnetic interferences and nanostractures. We have found the x-ray nonreciprocal directional dichroism not only in GaFeO3 but also Fe3O4.

我们研究了新的磁光效应，称为“磁电光效应”和“磁手性效应”。在这些光学效应中，去偏振光的光学响应取决于传播矢量的方向。本文研究了铁磁体、GaFeO3和尖晶石型Fe3O4单晶的光学特性，以阐明磁电光学效应和磁手性效应的机理。GaFeO3在低温下具有自发磁化和电极化，表明空间反演对称性和时间反演对称性被破坏，而Fe3O4具有局部空间反演对称性。本文研究了极性铁磁体GaFeO3在1.0 ~ 2.5 eV能量范围内的磁电光效应，即光传播方向反转时光吸收的变化。此外，我们还发现了一种新的磁光效应，称为x射线非互反定向二色性，即Fe离子K边附近的x射线吸收取决于x射线传播矢量与GaFeO3中磁化和电极化矢量的外部产生是平行还是反平行。这些光学响应表现出明显的依赖于电极化和磁化，表明这些光学效应与环面力矩之间的关系。本文所展示的x射线非互反定向二色光谱可以作为一种有用的工具来证明非中心对称系统（如磁干扰和纳米结构）中的局部磁性。我们不仅发现了GaFeO3，而且发现了Fe3O4的x射线非倒易定向二色性。