论文标题
将高阶拓扑与过渡金属二分法单层中的轨道霍尔效应联系起来
Connecting Higher-Order Topology with the Orbital Hall Effect in Monolayers of Transition Metal Dichalcogenides
论文作者
论文摘要
在2H结构相中，过渡金属二分法元素（TMD）的单层已被归类为高阶拓扑绝缘子（HOTI），受到$ C_3 $旋转对称性的保护。此外，理论计算显示了TMD的绝缘缝隙中的轨道霍尔高原，其特征是轨道Chern数。我们探索了两个结构阶段中TMD单层中这两种现象之间的相关性：非中心对称2H和中心对称1T。使用密度函数理论，我们确认了2H-TMD的特征，并揭示了1T-TMDS由$ \ Mathbb {z} _4 $拓扑不变性识别。结果，当沿着适当的方向切割时，它们会托管带边缘的边缘，这些边缘跨越了其大块的能带间隙并可以运输轨道角动量。因此，我们的线性响应计算表明HOTI阶段伴随着轨道霍尔的效应。使用一般的对称参数，我们在两个现象之间建立了对自旋甲膦型的潜在影响的联系。
Monolayers of transition metal dichalcogenides (TMDs) in the 2H structural phase have been recently classified as higher-order topological insulators (HOTI), protected by $C_3$ rotation symmetry. In addition, theoretical calculations show an orbital Hall plateau in the insulating gap of TMDs, characterized by an orbital Chern number. We explore the correlation between these two phenomena in TMD monolayers in two structural phases: the noncentrosymmetric 2H and the centrosymmetric 1T. Using density functional theory, we confirm the characteristics of 2H-TMDs and reveal that 1T-TMDs are identified by a $\mathbb{Z}_4$ topological invariant. As a result, when cut along appropriate directions, they host conducting edge-states, which cross their bulk energy-band gaps and can transport orbital angular momentum. Our linear response calculations thus indicate that the HOTI phase is accompanied by an orbital Hall effect. Using general symmetry arguments, we establish a connection between the two phenomena with potential implications for spin-orbitronics.
