Weak topological insulators, nodal-line semimetals, and Dirac semimetals in phononic crystal plates

• Published in: Thin-walled structures Vol. 204; p. 112306
• Main Authors: Duan, Guiju, Zheng, Shengjie, Lin, Zhi-Kang, Xia, Baizhan
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.11.2024
• Subjects: 2D mechanical systems; Dirac semimetal phases; Edge states; Nodal-line semimetal phases; Phononic crystal plates; Weak topological insulator phases; Nodal-line semimetal phases; Phononic crystal plates; 2D mechanical systems; Dirac semimetal phases; Edge states; Weak topological insulator phases
• ISSN: 0263-8231
• DOI: 10.1016/j.tws.2024.112306

•The weak topological insulator phases, nodal-line semimetal phases, and dirac semimetal phases are observed in 2D mechanical systems.•The robustness of the edge states of the weak topological insulators is numerically demonstrated.•The edge states of the weak topological insulators are experimentally demonstrated. Topological phases of matter help us to modulate elastic waves at the boundaries of mechanical systems with robustness against defects. Here, we propose to realize weak topological insulator phases, nodal-line semimetal phases, and Dirac semimetal phases in 2D mechanical systems. We implement this idea by theoretical analysis of tight-binding models and numerical simulations of phononic crystal plates based on the two-dimensional Su-Schrieffer-Heeger models. The topological nature of these topological phases is characterized by the topological invariants. The edge states, the visualization feature of the weak topological insulators, are observed unambiguously in the phononic crystal plates. Particularly, the robustness of these edge states against structural defects is verified by removing four single square plates from the center. Experimentally, we realize two types of weak topological insulators in 2D mechanical systems. This study fertilizes the topological phases in mechanical systems and opens excellent avenues for manipulating elastic wave propagation.