Probing fragile topology with a screw dislocation

• DOI: 10.48550/arxiv.2405.02057
• Publication Date: 2024-05-03
• Authors: Ying Wu; Zhi‐Kang Lin; Yating Yang; Zhida Song; Feng Li; Jianhua Jiang
• Keywords: Condensed Matter - Materials Science; Condensed Matter - Mesoscale and Nanoscale Physics; Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Materials Science (cond-mat.mtrl-sci); FOS: Physical sciences; Physics - Optics; Optics (physics.optics)

Fragile topology, akin to twisted bilayer graphene and the exotic phases therein, is a notable topological class with intriguing properties. However, due its unique nature lack of bulk-edge correspondence, experimental signature fragile topology has been under debated since birth. Here, we demonstrate experimentally that filling anomaly can be probed via screw dislocations, despite they do not support gapless edge states. Using designer hexagonal phononic crystal band gap, find 1D bound modes emerge at dislocation bulk topology. We then establish connection between our system boundary condition gauge invariance principle illustrate such an emergent phenomenon intrinsic property anomaly. observe states using pump-probe measurements their dispersion wavefunctions, which unveils novel bulk-defect correspondence powerful tool for probing materials.