近日，上海交通大学蔡星汉团队实现了二维层状反铁磁体中超弱平面内磁各向异性的探测。2025年4月8日出版的《美国科学院院刊》杂志发表了这项成果。
磁各向异性在决定二维磁系统的临界行为和相变方面起着至关重要的作用。薄膜自旋电子器件的设计也需要它。尽管具有重要意义，但在范德瓦尔斯反铁磁/亚铁磁材料中，感知极其微弱的各向异性已被证明具有挑战性。
研究组首先对具有弱附加单轴各向异性的几层易平面反铁磁系统中的微磁能函数进行了模拟，并揭示了与低场自旋翻转行为密切相关的有趣的奇偶效应。他们还对表现出接近理想易平面各向异性的二维反铁磁绝缘体CrCl3模型进行了隧道磁导率测量。
低温下磁场控制的隧穿电流与模拟的平面内各向异性自旋配置很好地对齐，为检测1mT左右的磁各向异性场提供了直接的实验证据。该工作为精细表征二维反铁磁/亚铁磁系统中的磁结构和行为创造了机会，在数据存储和磁传感等自旋电子学中具有潜在的应用。
附：英文原文
Title: Probing ultraweak in-plane magnetic anisotropy within a two-dimensional layered antiferromagnet
Author: Fan, Yijie, Xu, Yihong, Bian, Renji, Zhang, Ruan, Mei, Junning, Wu, Jiaxin, Xie, Binghe, Zhu, Shuangxing, Chen, Yu, Gu, Feifan, Liu, Ying, Taniguchi, Takashi, Watanabe, Kenji, Liu, Fucai, Cai, Xinghan
Issue&Volume: 2025-4-8
Abstract: Magnetic anisotropy plays a crucial role in determining the critical behavior and phase transitions in two-dimensional magnetic systems. It is also required for the design of thin-film spintronic devices. Despite its significance, sensing extremely weak anisotropy has proven challenging in van der Waals antiferromagnetic/ferrimagnetic materials. Here, we first employ simulations of micromagnetic energy function in few-layer easy-plane antiferromagnetic systems with a weak additional uniaxial anisotropy and unveil an intriguing even–odd effect closely linked to low-field spin–flop behaviors. We further perform tunneling magneto-conductance measurements on a model 2D antiferromagnetic insulator, CrCl3, exhibiting near-ideal easy-plane anisotropy. The magnetic field-controlled tunneling current at low temperature aligns well with simulated in-plane anisotropic spin-configuration, providing direct experimental evidence for detecting magnetic anisotropy field around 1 mT. Our work creates opportunities for finely characterizing magnetic structures and behaviors in 2D antiferromagnetic/ferrimagnetic systems, with potential applications in spintronics such as data storage and magnetic sensing.
DOI: 10.1073/pnas.2414668122
Source: https://www.pnas.org/doi/abs/10.1073/pnas.2414668122