Pan Baoru, Zhou Pan, Lyu Pengbo, Xiao Huaping, Yang Xuejuan, Sun Lizhong
Xiangtan University, Hunan Provincial Key laboratory of Thin Film Materials and Devices, School of Materials Science and Engineering, Xiangtan 411105, People's Republic of China.
Xiangtan University, School of Physics and Optoelectronics, Xiangtan 411105, People's Republic of China.
Phys Rev Lett. 2024 Oct 18;133(16):166701. doi: 10.1103/PhysRevLett.133.166701.
Two-dimensional (2D) altermagnetism was recently proposed to be attainable in twisted antiferromagnetic bilayers providing an experimentally feasible approach to realize it in 2D materials. Nevertheless, a comprehensive understanding of the mechanism governing the appearance of altermagnetism in bilayer systems is still absent. In the present Letter, we address this gap by introducing a general stacking theory (GST) as a key condition for the emergence of altermagnetism in bilayer systems. The GST provides straightforward criteria to predict whether a bilayer demonstrates altermagnetic spin splitting, solely based on the layer groups of the composing monolayers. According to the GST, only seven point groups of bilayers facilitate the emergence of altermagnetism. It is revealed that, beyond the previously proposed antiferromagnetic twisted Van der Waals stacking, altermagnetism can even emerge in bilayers formed through the symmetrically restricted direct stacking of two monolayers. By combining the GST and first-principles calculations, we present illustrative examples of bilayers demonstrating altermagnetism. Our work establishes a robust framework for designing diverse bilayer systems with altermagnetism, thereby opening up new avenues for both fundamental research and practical applications in this field.
二维交变磁性最近被提出可在扭曲反铁磁双层中实现，这为在二维材料中实现它提供了一种实验上可行的方法。然而，对于双层系统中交变磁性出现的机制仍缺乏全面的理解。在本信函中，我们通过引入一种通用堆叠理论（GST）来填补这一空白，该理论是双层系统中出现交变磁性的关键条件。GST提供了直接的标准，仅基于组成单层的层群来预测双层是否表现出交变磁自旋分裂。根据GST，只有七种双层点群有利于交变磁性的出现。结果表明，除了先前提出的反铁磁扭曲范德华堆叠之外，交变磁性甚至可以在通过两个单层的对称受限直接堆叠形成的双层中出现。通过结合GST和第一性原理计算，我们给出了表现出交变磁性的双层的示例。我们的工作建立了一个用于设计具有交变磁性的各种双层系统的稳健框架，从而为该领域的基础研究和实际应用开辟了新途径。
