近日，美国密歇根大学的赵刘燕课题组与德州理工大学的Rui He等人合作并取得一项新进展，经过不懈努力，他们找到了磁性莫尔（Moiré）超晶格中存在非共线自旋纹理的证据。相关研究成果已于2023年5月18日在国际知名学术期刊《自然—物理学》上发表。
该研究小组报道了在二维扭曲双层CrI3中存在非共线自旋纹理的证据。通过逐渐的自旋转向（spin flop）过程，研究人员能够区分非共线自旋和共线自旋中突然的自旋翻转（spin flip）跃迁，并确定了由共线自旋产生的净磁化。此外，他们的研究还表明，在扭曲角度从0.5°到5°的范围内，非共线自旋和净磁化同时存在，尤其在1.1°时表现最为显著。研究人员测得在1.1°扭曲角度下样品的临界温度为25K，并观察到非共线自旋的软化现象。值得注意的是，这一临界温度明显低于天然少层中的Néel温度45K。这些研究结果为探索具有非共线自旋的非平凡磁性提供了一个平台。
据了解，莫尔磁性作为一种平台，正在崭露头角，用于设计和控制扭曲的磁性二维晶体中的奇异磁相。其中一个最重要的结果是非共线自旋纹理，它在共线自旋的扭曲二维磁体中出现，并为实现非平凡的磁序和激发提供了基础。然而，尽管最近进行了理论和实验努力，但莫尔磁性中的非共线自旋仍然缺乏直接的实验观测。
附：英文原文
Title: Evidence of non-collinear spin texture in magnetic moiré superlattices
Author: Xie, Hongchao, Luo, Xiangpeng, Ye, Zhipeng, Sun, Zeliang, Ye, Gaihua, Sung, Suk Hyun, Ge, Haiwen, Yan, Shaohua, Fu, Yang, Tian, Shangjie, Lei, Hechang, Sun, Kai, Hovden, Robert, He, Rui, Zhao, Liuyan
Issue&Volume: 2023-05-18
Abstract: Moiré magnetism is emerging as a platform to design and control exotic magnetic phases in twisted magnetic two-dimensional crystals. Non-collinear spin texture emerging from twisted two-dimensional magnets with collinear spins is one of the most profound consequences of moiré magnetism and forms the basis for realizing non-trivial magnetic orders and excitations. However, no direct experimental observations of non-collinear spins in moiré magnets have been made, despite recent theoretical and experimental efforts. Here, we report evidence of non-collinear spin texture in two-dimensional twisted double bilayer CrI3. We distinguish the non-collinear spins with a gradual spin flop process from the collinear spins with sudden spin flip transitions and identify a net magnetization emerging from the collinear spins. We also demonstrate that both non-collinear spins and net magnetization are present at twist angles from 0.5° to 5° but are most prominent for 1.1°. We resolve a critical temperature of 25K for the onset of the net magnetization and the softening of the non-collinear spins in the 1.1° samples. This is substantially lower than the Néel temperature of 45K for natural few layers. Our results provide a platform to explore non-trivial magnetism with non-collinear spins.
DOI: 10.1038/s41567-023-02061-z
Source: https://www.nature.com/articles/s41567-023-02061-z