论文标题
范德华（Van der Waals
Higher-order Topological Phases of Magnons in van der Waals Honeycomb Ferromagnets
论文作者
论文摘要
从理论上讲，我们通过用抗磁性层间层偶联堆叠范德华蜂窝铁磁体来提出二阶拓扑磁化绝缘子。该系统展示了Z $ _ {2} $拓扑阶段，受伪时间反转对称（PTR）保护。易于平面各向异性术语破坏了PTR并破坏拓扑阶段。然而，它尊重磁性两倍的旋转对称性，该旋转对称性可以保护二阶拓扑阶段，其沿双层中的角模式和沿堆叠方向的铰链模式。此外，引入的交错层间耦合建立了一个z $ _ {2} $$ \ times $ z拓扑，从而产生了带有非零Chern号码的间隙拓扑表面模式。因此，手性铰链模式沿着水平的铰链传播，并以立方几何形状传播，并且对疾病具有鲁棒性。我们的工作桥接了Van der Waals平台中的高阶拓扑和镁质，可用于构建拓扑磁通设备。
We theoretically propose a second-order topological magnon insulator by stacking the van der Waals honeycomb ferromagnets with antiferromagnetic interlayer coupling. The system exhibits Z$_{2}$ topological phase, protected by pseudo-time-reversal symmetry (PTRS). An easy-plane anisotropy term breaks PTRS and destroys the topological phase. Nevertheless, it respects a magnetic two-fold rotational symmetry which protects a second-order topological phase with corner modes in bilayer and hinge modes along stacking direction. Moreover, an introduced staggered interlayer coupling establishes a Z$_{2}$$\times$Z topology, giving rise to gapped topological surface modes carrying non-zero Chern numbers. Consequently, chiral hinge modes propagate along the horizontal hinges in a cuboid geometry and are robust against disorders. Our work bridges the higher-order topology and magnons in van der Waals platforms, and could be used for constructing topological magnonic devices.
