Fang Fang, Yu Yanwei, Zhang Li, Li Yang
The Engineering and Technology Research Center of Myocardial Prevention and Rehabilitation, The Fourth Medical College of Harbin Medical University, Harbin, China.
TOF-PET/CT/MR Center, The Fourth Medical College of Harbin Medical University, Harbin, China.
Front Chem. 2024 Dec 2;12:1500989. doi: 10.3389/fchem.2024.1500989. eCollection 2024.
In recent years, the exploration of topological states within two-dimensional materials has emerged as a compelling focus, complementing their three-dimensional counterparts. Through theoretical calculations, we unveil the exceptional topological state in the monolayer lithium hydrosulfide, where an ideal hourglass nodal loop is identified. Notably, this nodal loop is characterized by only four bands, representing the simplest configuration for realizing hourglass dispersion. We provide detailed symmetry arguments alongside model calculations to elucidate the formation mechanism of the nodal loop and its corresponding hourglass dispersion. Moreover, the associated edge states are not only well-separated from the bulk band projection but also persist consistently throughout the Brillouin zone. Due to the lightweight constitutive elements of this material, both the hourglass dispersion and the edge states remain robust even in the presence of spin-orbit coupling. To enhance its practical applicability, we have evaluated various mechanical parameters, analyzing their anisotropic behaviors. Furthermore, we examined the material's response to strain conditions under both compressive and tensile stress, uncovering distinct variations in energy, size, and the hourglass dispersion of the nodal loop. Overall, the hourglass nodal loop state explored in this study, along with the proposed material candidate, provides a strong foundation for future experimental investigations. This research potentially paves the way for significant advancements within this emerging field.
近年来，二维材料中拓扑态的探索已成为一个引人注目的焦点，对其三维对应物起到补充作用。通过理论计算，我们揭示了单层硫化氢锂中的特殊拓扑态，其中识别出了一个理想的沙漏型节线环。值得注意的是，这个节线环仅由四个能带表征，代表了实现沙漏型色散的最简单构型。我们提供了详细的对称性论证以及模型计算，以阐明节线环及其相应沙漏型色散的形成机制。此外，相关的边缘态不仅与体态投影很好地分离，而且在整个布里渊区都持续存在。由于这种材料的组成元素较轻，即使存在自旋轨道耦合，沙漏型色散和边缘态仍然很稳健。为了提高其实际适用性，我们评估了各种力学参数，分析了它们的各向异性行为。此外，我们研究了材料在压缩和拉伸应力下对应变条件的响应，发现节线环的能量、尺寸和沙漏型色散存在明显变化。总体而言，本研究中探索的沙漏型节线环态以及所提出的候选材料，为未来的实验研究提供了坚实的基础。这项研究可能为这一新兴领域的重大进展铺平道路。
