论文标题
磁性涡流呼吸方晶格中的二阶拓扑绝缘子
Second-order topological insulator in breathing square lattice of magnetic vortices
论文作者
论文摘要
我们研究了磁涡旋的偶尔耦合二维呼吸方晶格中的拓扑阶段。通过评估量化的Chern号码和$ \ Mathbb {Z} _ {4} $ Berry阶段，我们获得了相位图，并确定仅当交替键长的比率超出临界值之比时，才出现二阶拓扑角状态。有趣的是，我们通过求解广义的Thiele方程，在不同频率的不同频率下发现了三个角状态，该方程在冷凝物质系统中没有对应。我们表明，新兴角状态在拓扑上受到四分之一晶格的普遍性手性对称性的保护，从而导致对疾病和缺陷的特殊鲁棒性。完整的微磁模拟通过很好的一致性证实了理论预测。基于涡流的成像设备被设计为二阶磁性绝缘体的现实应用的演示。我们的发现为实现对称性保护的多带角状态提供了一条途径，这些状态有望实现Spintronic高阶拓扑设备。
We study the topological phase in dipolar-coupled two-dimensional breathing square lattice of magnetic vortices. By evaluating the quantized Chern number and $\mathbb{Z}_{4}$ Berry phase, we obtain the phase diagram and identify that the second-order topological corner states appear only when the ratio of alternating bond lengths goes beyond a critical value. Interestingly, we uncover three corner states at different frequencies ranging from sub GHz to tens of GHz by solving the generalized Thiele's equation, which has no counterpart in condensed matter system. We show that the emerging corner states are topologically protected by a generalized chiral symmetry of the quadripartite lattice, leading to particular robustness against disorder and defects. Full micromagnetic simulations confirm theoretical predictions with a great agreement. A vortex-based imaging device is designed as a demonstration of the real-world application of the second-order magnetic topological insulator. Our findings provide a route for realizing symmetry-protected multi-band corner states that are promising to achieve spintronic higher-order topological devices.
