论文标题

自dual Kagome超材料的动力和脆弱拓扑的出现

Dynamics of self-dual kagome metamaterials and the emergence of fragile topology

论文作者

Azizi, Pegah, Sarkar, Siddhartha, Sun, Kai, Gonella, Stefano

论文摘要

近年来,发现具有脆弱拓扑状态的系统。这些物质状态缺乏某些通常与拓扑相关的保护属性,因此具有使它们难以捉摸的较弱的签名。此外,它们通常仅限于特殊的对称类别,通常在语音媒体的背景下很少研究。在这封信中,我们从理论上预测了易碎的拓扑带中的易碎拓扑带的出现,在所谓的自偶型构型中,带有三倍旋转对称性的扭曲的kagome弹性晶格的出现。一个必要的要求是晶格是一种结构性超材料,其中铰链的作用由弹性有限厚的韧带扮演。边界易碎拓扑状态的带隙中出现的边缘模式之间的相互作用也导致了有限六角形域的选定角落的角模式的出现,该模式将晶格作为二阶拓扑绝缘子有资格。我们通过在物理原型上进行的3D扫描激光多普勒振动法通过一系列实验来证明我们的发现。所选的配置在表现出脆弱拓扑的动态系统的全景中引人注目的几何简单和易于物理实现。

Recent years have seen the discovery of systems featuring fragile topological states. These states of matter lack certain protection attributes typically associated with topology and are therefore characterized by weaker signatures that make them elusive to observe. Moreover, they are typically confined to special symmetry classes and, in general, rarely studied in the context of phononic media. In this Letter, we theoretically predict the emergence of fragile topological bands in the spectrum of a twisted kagome elastic lattice with three-fold rotational symmetry, in the so-called self-dual configuration. A necessary requirement is that the lattice is a structural metamaterial, in which the role of the hinges is played by elastic finite-thickness ligaments. The interplay between the edge modes appearing in the bandgaps bounding the fragile topological states is also responsible for the emergence of corner modes at selected corners of a finite hexagonal domain, which qualifies the lattice as a second-order topological insulator. We demonstrate our findings through a series of experiments via 3D Scanning Laser Doppler Vibrometry conducted on a physical prototype. The selected configuration stands out for its remarkable geometric simplicity and ease of physical implementation in the panorama of dynamical systems exhibiting fragile topology.

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