近日，美国德克萨斯大学奥斯汀分校的Edoardo Baldini及其研究小组与德国马克斯·普朗克物质结构与动力学研究所的Angel Rubio等人合作并取得一项新进展。经过不懈努力，他们揭示范德华多铁性材料中的巨大手性磁电振荡。相关研究成果已于2024年7月17日在国际权威学术期刊《自然》上发表。

本文对剥离范德华多铁性材料中对映异构体域的动态磁电耦合进行了精确测量。研究人员在集体电子磁子模式下的共振中评估了这种相互作用，用一套超快光学探针捕捉了其振荡对材料的偶极和磁阶的影响。数据显示，在太赫兹频率上存在巨大的自然光学活性，其特征是电极化和磁化分量之间的正交调制。

第一性原理计算进一步表明，这些手性耦合源于非共线自旋织构和相对论性自旋轨道相互作用之间的协同作用，导致晶格介导效应的实质性增强。这项研究结果凸显了缠绕序在二维极限下实现独特功能的潜力，并为在太赫兹速度下工作的范德华磁电器件的发展铺平了道路。

据悉，螺旋自旋结构是磁致手性的表现形式，使材料中的偶极序和磁序相互纠缠。最近发现的螺旋范德华多铁性材料直至超薄极限，提高了二维大手性磁电相关的前景。然而，到目前为止，这些耦合的确切性质和大小仍然未知。

附：英文原文

Title: Giant chiral magnetoelectric oscillations in a van der Waals multiferroic

Author: Gao, Frank Y., Peng, Xinyue, Cheng, Xinle, Vias Bostrm, Emil, Kim, Dong Seob, Jain, Ravish K., Vishnu, Deepak, Raju, Kalaivanan, Sankar, Raman, Lee, Shang-Fan, Sentef, Michael A., Kurumaji, Takashi, Li, Xiaoqin, Tang, Peizhe, Rubio, Angel, Baldini, Edoardo

Issue&Volume: 2024-07-17

Abstract: Helical spin structures are expressions of magnetically induced chirality, entangling the dipolar and magnetic orders in materials. The recent discovery of helical van der Waals multiferroics down to the ultrathin limit raises prospects of large chiral magnetoelectric correlations in two dimensions. However, the exact nature and magnitude of these couplings have remained unknown so far. Here we perform a precision measurement of the dynamical magnetoelectric coupling for an enantiopure domain in an exfoliated van der Waals multiferroic. We evaluate this interaction in resonance with a collective electromagnon mode, capturing the impact of its oscillations on the dipolar and magnetic orders of the material with a suite of ultrafast optical probes. Our data show a giant natural optical activity at terahertz frequencies, characterized by quadrature modulations between the electric polarization and magnetization components. First-principles calculations further show that these chiral couplings originate from the synergy between the non-collinear spin texture and relativistic spin–orbit interactions, resulting in substantial enhancements over lattice-mediated effects. Our findings highlight the potential for intertwined orders to enable unique functionalities in the two-dimensional limit and pave the way for the development of van der Waals magnetoelectric devices operating at terahertz speeds.

DOI: 10.1038/s41586-024-07678-5

Source: https://www.nature.com/articles/s41586-024-07678-5