论文标题
高阶Weyl半法
Higher-order Weyl Semimetals
论文作者
论文摘要
我们研究具有附着在表面和铰链费米弧上的散装Weyl节点的高阶Weyl半含量（HOWSM）。我们确定了一种新型的Weyl节点，它可以将$ 2nd $顺序的Weyl节点配置为$ 2nd $ order节点，该节点可以识别为在动量空间中的过渡，在该空间中，Chern数字和更高阶的拓扑不变变化。作为概念的证明，我们使用堆叠的高阶四极杆绝缘子的模型来识别三种类型的WSM阶段：$ 1st $ - 订单，$ 2nd $ - order和Hybrid-order。该模型还可以实现具有各种表面和铰链弧的II型和混合式WSM。此外，我们表明在磁通量存在下电荷密度的测量可以帮助识别某些类别的$ 2nd $ order wsms。值得注意的是，我们发现将$ 2nd $订购的Weyl相和常规的$ 1st $ - 订单耦合，可以导致具有共存的表面锥和平坦的铰链弧并不独立且不连接的混合级拓扑绝缘子。最后，我们表明可以将定期驾驶用作生成HOWSM的一种方式。我们的结果与超材料以及CD $ _3 $的各个阶段相关，为$ _2 $，kmgbi和Rutile structure pto $ _2 $，这些$ _2 $预计可以实现高阶Dirac Semimetals。
We investigate higher-order Weyl semimetals (HOWSMs) having bulk Weyl nodes attached to both surface and hinge Fermi arcs. We identify a new type of Weyl node, that we dub a $2nd$ order Weyl node, that can be identified as a transition in momentum space in which both the Chern number and a higher order topological invariant change. As a proof of concept we use a model of stacked higher order quadrupole insulators to identify three types of WSM phases: $1st$-order, $2nd$-order, and hybrid-order. The model can also realize type-II and hybrid-tilt WSMs with various surface and hinge arcs. Moreover, we show that a measurement of charge density in the presence of magnetic flux can help identify some classes of $2nd$ order WSMs. Remarkably, we find that coupling a $2nd$-order Weyl phase with a conventional $1st$-order one can lead to a hybrid-order topological insulator having coexisting surface cones and flat hinge arcs that are independent and not attached to each other. Finally, we show that periodic driving can be utilized as a way for generating HOWSMs. Our results are relevant to metamaterials as well as various phases of Cd$_3$As$_2$, KMgBi, and rutile-structure PtO$_2$ that have been predicted to realize higher order Dirac semimetals.
