AI 中文总结
研究公度扭转可驱动堆叠双层CrO发生磁性拓扑相变，将其转变为两类外尔半金属，且外尔相受特定自旋对称性保护，为构建磁性拓扑相提供了对称调控途径。
AI 中文摘要
层间扭转为调控电子态提供了几何途径，但它能否同时重构磁对称性和能带拓扑仍不清楚。本文基于对称性分析和第一性原理计算，证明公度扭转可驱动堆叠双层CrO发生磁性拓扑相变，具体而言，它将反铁磁狄拉克半金属转变为d波反常磁双极化外尔半金属或非常规补偿型磁性外尔半金属。关键结果是，d波反常磁相中的外尔点位于布里渊区的一般k点，受自旋对称性{C₂T||C₂zT}保护，这与常规二维外尔半金属形成鲜明对比，后者的外尔点通常受镜面或旋转对称性保护，因此被钉扎在高对称线上。我们进一步证明，公度扭转可保留自旋对称性{C₂T||C₂zT}，使外尔相成为扭转的鲁棒结果，而非特定角度的微调特征。本研究建立了一种基于对称性的方法，用于在扭转二维材料中构建磁性拓扑相。
英文摘要
Interlayer twisting offers a geometric route to controlling electronic states, but whether it can simultaneously reconstruct magnetic symmetry and band topology remains unclear. Here, based on symmetry analysis and first-principles calculations, we show that commensurate twisting drives magnetic topological phase transitions in stacked bilayer CrO. In particular, it transforms an antiferromagnetic Dirac semimetal into either a $d$-wave altermagnetic bipolarized Weyl semimetal or an unconventional compensated magnetic Weyl semimetal. A key result is that the Weyl points in the $d$-wave altermagnetic phase lie at generic $k$ points in the Brillouin zone and are protected by the spin symmetry $\left\{ C_2 T||C_{2z} T\right\}$. This sharply contrasts with conventional two-dimensional Weyl semimetals, where Weyl points are typically protected by mirror or rotational symmetries and thus pinned to high-symmetry lines. We further show that commensurate twisting preserves the spin symmetry $\left\{ C_2 T||C_{2z} T\right\}$, making the Weyl phase a robust consequence of twisting rather than a fine-tuned feature of a specific angle. Our work establishes a symmetry-based route to engineering magnetic topological phases in twisted two-dimensional materials.
Comments7 pages, 5 figures
