近日，美国罗格斯大学Cheong, Sang-Wook团队报道了电环面的不变性产生明显的横向电磁响应。这一研究成果发表在2025年11月24日出版的《自然—物理学》杂志上。
在保持空间反演对称性或时间反演对称性的体系中，电磁效应的横向响应（如反常霍尔效应、法拉第旋转、非互易方向性二色性及非对角线性磁电效应）通常与磁环形不变性框架相关。
研究组提出了一类新的横向电磁响应，其源于铁旋转体系中电环形不变性的自发破缺，而该体系同时保持空间反演和时间反演对称性。这种机制与磁环形不变性主导的响应存在本质差异。研究组通过掺杂钛铁矿FeTiO3的实验，观测到铁旋转畴的高阶非对角磁化率以及畴壁处线性对角磁化率的显著降低。研究结果揭示了具有自发电环形矩的铁旋转材料中异常的横向磁化率。因此，该工作展示了铁旋转材料在新型电磁功能器件中的潜在应用前景。
附：英文原文
Title: Electric toroidal invariance generates distinct transverse electromagnetic responses
Author: Du, Kai, Jo, Daegeun, Xu, Xianghan, Huang, Fei-Ting, Lee, Ming-Hao, Chu, Ming-Wen, Wang, Kefeng, Guo, Xiaoyu, Zhao, Liuyan, Vanderbilt, David, Lee, Hyun-Woo, Cheong, Sang-Wook
Issue&Volume: 2025-11-24
Abstract: Breaking spatial-inversion or time-reversal symmetry in solids leads to transverse electromagnetic effects such as the anomalous Hall effect, Faraday rotation, non-reciprocal directional dichroism and off-diagonal linear magnetoelectricity. These are all tied to the framework of magnetic toroidal invariance. Here we introduce a distinct class of transverse electromagnetic responses that arise from electric toroidal invariance in ferro-rotational systems that preserve both inversion and time-reversal symmetries. It is different from that governed by magnetic toroidal invariance. We demonstrate a high-order off-diagonal magnetic susceptibility of ferro-rotational domains and a reduced linear diagonal magnetic susceptibility at these domain walls in doped ilmenite FeTiO3. Our results reveal the presence of anomalous transverse susceptibilities in ferro-rotational materials with spontaneous electric toroidal moments. Therefore, our findings illustrate emergent functionalities of ferro-rotational materials. Magnetic toroidal invariance generates transverse electromagnetic effects in materials with broken symmetries. Now a distinct magnetic response is shown to emerge in ferro-rotational systems in which both inversion and time-reversal symmetries are preserved.
DOI: 10.1038/s41567-025-03100-7
Source: https://www.nature.com/articles/s41567-025-03100-7