Session: 01-02-01: Topological Phononics

Paper Number: 143224

143224 - Topologically Protected Domain Wall Modes in Fragile Topology: Unveiling the Dynamics of Self-Dual Twisted Kagome Lattices 

Fragile topological states of matter, typically characterized by a lack of conventional protective features associated with topology, often exhibit relatively weak manifestations. Their strength is intricately influenced by system symmetry and boundaries, presenting challenges for observation across diverse symmetries and remaining extremely rare in phononic media. In this study, we introduce a theoretical framework predicting the emergence of fragile topological bands within a self-dual twisted kagome lattice. We model the lattice hinges as elastic, finite-thickness ligaments capable of storing bending energy. Expanding on this theoretical prediction, we also explore the emergence of domain wall modes featuring robust signatures. This is achieved through the design of twisted kagome bi-domains, comprising two topologically distinct sublattices—one trivial and the other exhibiting fragile topological characteristics—sharing a common bandgap and meeting at a domain wall. To validate our theoretical findings, we conducted a series of experiments using physical prototypes and 3D Scanning Laser Doppler Vibrometry. Our experimental results successfully corroborate the theoretical predictions, confirming the emergence of fragile topological states and the presence of robust domain wall modes in this specific system. Notably, the selected configuration stands out for its geometric simplicity and ease of physical implementation in the panorama of dynamical systems exhibiting fragile topology.

Presenting Author: Pegah Azizi University of Minnesota

Presenting Author Biography: I am currently a third-year Ph.D. student at the University of Minnesota, conducting research under the guidance of Professor Gonella. My work revolves around the numerical simulation and experimental exploration, with a specific focus on periodic structures and phononic metamaterials.

Authors:

Pegah Azizi University of Minnesota
Siddhartha Sarkar University of Michigan
Kai Sun University of Michigan
Stefano Gonella University of Minnesota