Magneto-electric optics in non-centrosymmetric ferromagnets
Magneto-electric optics in non-centrosymmetric ferromagnets
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DOI：
10.1088/0953-8984/20/43/434211
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发表时间：
2008-10-29
影响因子：
2.7
通讯作者：
Arima, T.
中科院分区：
文献类型：
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作者：
Arima, T.
非中心对称铁磁材料可以表现出磁电学所特有的光学和X射线响应。例如，折射率和吸收系数可能依赖于光(x射线)传播方向k和磁化强度M，这些依赖关系可以分别称为定向双折射和定向二向色性。最近在GaFeO(3)和CuB(2)O(4)中观察到了这种磁电(ME)光学性质。ME光学可以从微观角度解释为非中心对称磁位上的电偶极子(E1)过程与磁偶极子(M1)或电四极(E2)过程的干涉。即使在具有全局反转对称性的磁性晶体中，也可以在局部反转破裂的磁位上发生E_1-E_2干涉，从而产生独特的X射线衍射。在GaFeO_3和Fe(3)O(4)中发现了这种与ME效应有关的X射线衍射。利用目前使用的光刻等技术对空间反转进行人工破缺，可以应用于多铁体的探测，作为研究ME光学的一种方式。在这种定制的多铁性材料的衍射中，成功地观察到了室温下较大的ME光信号。
Non-centrosymmetric ferromagnetic materials can show optical and x-ray responses unique to magneto-electrics. For example, the refractive index and absorption coefficient may be dependent on the directions of light (x-ray) propagation k and magnetization M, and these dependences can be termed directional birefringence and directional dichroism, respectively. Such a kind of magneto-electric (ME) optics has recently been observed in GaFeO(3) and CuB(2)O(4). The ME optics can be explained from the microscopic point of view by the interference of an electric dipole (E1) process with a magnetic dipole (M1) or electric quadrupole (E2) process at non-centrosymmetric magnetic sites. Even in magnetic crystals with global inversion symmetry, the E1-E2 interference can occur at magnetic sites with local inversion breaking, causing unique x-ray diffraction. Such ME-effect-related x-ray diffraction has been found in GaFeO3 and Fe(3)O(4). Artificial breaking of space inversion by means of currently used techniques such as lithography can be applied to the exploration of multiferroics, as a way of investigating ME optics. Relatively large ME optical signals at room temperature have been successfully observed in diffraction from such tailor-made multiferroics.