Visualization of ferroaxial domains in an order-disorder type ferroaxial crystal
Visualization of ferroaxial domains in an order-disorder type ferroaxial crystal
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DOI：
10.1038/s41467-020-18408-6
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发表时间：
2020-09-11
影响因子：
16.6
通讯作者：
Kimura, T.
中科院分区：
文献类型：
--
作者：
Hayashida, T.;Uemura, Y.;Kimura, T.
铁轴材料表现出自发有序的旋转结构畸变与轴向矢量对称性已获得越来越多的关注，最近广泛的研究铁材料的动机。如在常规铁电体（例如，铁电体和铁磁体），则畴态将存在于铁轴材料中。然而，铁轴畴的观测是不平凡的，由于序参量的性质，这是不变的时间反演和空间反演操作。在这里，我们提出NiTiO 3是一个有序-无序型铁轴材料，并空间解决其铁轴畴，通过使用线性电回转效应：旋光正比于外加电场。为了检测电旋转的小信号（10（-5）度V-1的顺序），我们采用了最近开发的差分图像传感技术。此外，铁轴畴的纳米尺度的空间分辨率与扫描透射电子显微镜和会聚束电子衍射相结合的使用确认。畴可视化的成功将促进铁轴材料作为一种新的铁性物质态的研究。
Ferroaxial materials that exhibit spontaneous ordering of a rotational structural distortion with an axial vector symmetry have gained growing interest, motivated by recent extensive studies on ferroic materials. As in conventional ferroics (e.g., ferroelectrics and ferromagnetics), domain states will be present in the ferroaxial materials. However, the observation of ferroaxial domains is non-trivial due to the nature of the order parameter, which is invariant under both time-reversal and space-inversion operations. Here we propose that NiTiO3 is an order-disorder type ferroaxial material, and spatially resolve its ferroaxial domains by using linear electrogyration effect: optical rotation in proportion to an applied electric field. To detect small signals of electrogyration (order of 10(-5) deg V-1), we adopt a recently developed difference image-sensing technique. Furthermore, the ferroaxial domains are confirmed on nano-scale spatial resolution with a combined use of scanning transmission electron microscopy and convergent-beam electron diffraction. Our success of the domain visualization will promote the study of ferroaxial materials as a new ferroic state of matter.