Peierls-Nabarro barrier effect in nonlinear Floquet topological insulators

The Peierls-Nabarro barrier is a discrete effect that frequently occurs in nonlinear systems. A signature of the slowing and eventual stopping solitary waves. This work examines intense electromagnetic waves propagating through periodic honeycomb lattice helically-driven waveguides, which serves as paradigmatic Floquet topological insulator. Here it shown topologically protected edge modes do not suffer from typical slowdown associated with barrier. Instead, result their nature, always move forward redistribute energy: narrow (discrete) mode transforms into wide effectively continuous mode. On other hand, does eventually slow down stop propagating. Topological are initially naturally tend to envelope states described by generalized Schrodinger equation. These results provide insight nature insulators application.