Experimental realization of a reconfigurable electroacoustic topological insulator
Experimental realization of a reconfigurable electroacoustic topological insulator
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DOI：
10.1073/pnas.1920549117
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发表时间：
2020-07-14
影响因子：
11.1
通讯作者：
Leamy, Michael J.
中科院分区：
文献类型：
--
作者：
Darabi, Amir;Collet, Manuel;Leamy, Michael J.
引导弹性波的一个重大挑战是在尖锐的边缘、缺陷和无序处存在反射和散射。最近，机械拓扑绝缘体试图通过支持后向散射阻波传输来克服这一挑战。在本文中，我们提出并实验证明了一种可重构的电声拓扑绝缘体，它具有类似于量子谷霍尔效应(QVHE)的特性。利用可编程开关，这种声子结构允许磁区壁的快速重新配置，从而能够控制处于静态和有限频率区的声子沿动态界面的后向散射阻力波的传播。相应地，类石墨烯聚乳酸(PLA)层作为主体介质，配备了周期性排列和粘结的压电(PZT)贴片，导致在K点处形成两个狄拉克锥体。然后，将PZT贴片连接到负电容外部电路，以打破反转对称，产生非平凡的拓扑保护带隙。因此，在较宽的频率范围内，对于不同的预定轨迹，对拓扑保护的界面波进行了数值演示和验证。
A substantial challenge in guiding elastic waves is the presence of reflection and scattering at sharp edges, defects, and dis-order. Recently, mechanical topological insulators have sought to overcome this challenge by supporting back-scattering resis-tant wave transmission. In this paper, we propose and experi-mentally demonstrate a reconfigurable electroacoustic topolog-ical insulator exhibiting an analog to the quantum valley Hall effect (QVHE). Using programmable switches, this phononic struc-ture allows for rapid reconfiguration of domain walls and thus the ability to control back-scattering resistant wave propaga-tion along dynamic interfaces for phonons lying in static and finite-frequency regimes. Accordingly, a graphene-like polyac-tic acid (PLA) layer serves as the host medium, equipped with periodically arranged and bonded piezoelectric (PZT) patches, resulting in two Dirac cones at the K points. The PZT patches are then connected to negative capacitance external circuits to break inversion symmetry and create nontrivial topologi-cally protected bandgaps. As such, topologically protected inter-face waves are demonstrated numerically and validated exper-imentally for different predefined trajectories over a broad frequency range.