论文标题
零索引Weyl超材料
Zero-index Weyl metamaterials
论文作者
论文摘要
根据其费米表面的几何形状，在经典系统中的Weyl Semimetals及其类似物已分为两种类型。在I型Weyl半法（WSM）中，Weyl Point（WP）的锥状光谱不被倾斜，导致点状的闭合费米表面。相反，在II型WSM中，WP周围的能量光谱被强烈倾斜，因此费米表面从一个点转换为开放表面。在这里，我们在理论上和实验上都证明了一种新型的（经典）Weyl半学的新型，其费米表面既不是点，也不是表面，而是平坦的线。这种半学的独特费米表面被称为III型或零索引WSM，产生了独特的物理特性：半学的边缘模式之一沿特定方向表现出零折射的零索引，与I和II类型WSM呈鲜明对比，与I和II的II和II型WSM相比，该指数始终是非差异的指数。我们表明，此类拓扑阶段的零索引响应可以使令人兴奋的应用（例如非凡的波传输（EOT））。
Depending on the geometry of their Fermi surfaces, Weyl semimetals and their analogues in classical systems have been classified into two types. In type I Weyl semimetals (WSMs), the cone-like spectrum at the Weyl point (WP) is not tilted, leading to a point-like closed Fermi surface. In type II WSMs, on the contrary, the energy spectrum around the WP is strongly tilted such that the Fermi surface transforms from a point into an open surface. Here, we demonstrate, both theoretically and experimentally, a new type of (classical) Weyl semimetal whose Fermi surface is neither a point nor a surface, but a flat line. The distinctive Fermi surfaces of such semimetals, dubbed as type III or zero-index WSMs, gives rise to unique physical properties: one of the edge modes of the semimetal exhibits a zero index of refraction along a specific direction, in stark contrast to types I and II WSMs for which the index of refraction is always non-zero. We show that the zero-index response of such topological phases enables exciting applications such as extraordinary wave transmission (EOT).
