Emergence of Cascading Flat Bands in Breathing Superlattices

Abstract

Flat bands have become a pillar of modern condensed matter physics and photonics owing to the vanishing group velocity and diverging density of states. Here, we present a paradigmatic scheme to construct arbitrary flat bands on demand by introducing a new type breathing superlattice, where both the number and spectral positions of isolated flat bands can be continuously tailored by simply controlling the breathing strength. Microscopically, the momentum-independent interband scatterings near the band edge protect them robust against weak intra-cell disorder. By dimensional reduction, we establish a duality between the one-dimensional (1D) breathing superlattice and the 2D Harper-Hofstadter model, where cascade flat bands naturally emerge as the different orders of Landau levels in the weak magnetic flux limit. As a proof of concept, photonic flat bands at optical frequencies are experimentally demonstrated with all-dielectric photonic crystal slabs. Finally, we generalize our scheme to 2D systems to realize partial and omnidirectional flat bands, and discuss the achievement of high-quality factors. Our findings shed new light on the manipulation of flat bands with high band flatness and large usable bandwidth, paving the way for the development of advanced optical devices.

Please contact Moru Song or Yongliang Zhang for any sentific questions or comments/suggestions to this work

References in corpus (20)

• Topological Field Theory of Time-Reversal Invariant Insulators
• Flat Bands in Slightly Twisted Bilayer Graphene
• Observation of a localized flat-band state in a photonic Lieb lattice
• Observation of bound states in Lieb photonic lattices
• Localization and delocalization of light in photonic moire lattices
• Hybrid photonic-crystal fiber
• Inverse design of photonic crystals through automatic differentiation
• $\Gamma$-Valley Transition-Metal-Dichalcogenide Moirè Bands
• Observation of enhanced free-electron radiation from photonic flatband resonances
• Magic configurations in Moiré Superlattice of Bilayer Photonic crystal: Almost-Perfect Flatbands and Unconventional Localization
• Realization of robust boundary modes and non-contractible loop states in photonic Kagome lattices
• Bilayer Photonic Graphene
• Crystal Net Catalog of Model Flat Band Materials
• Designer Flat Bands in Quasi-One-Dimensional Atomic Lattices
• Topological exact flat bands in two dimensional materials under periodic strain
• Topological supermodes in photonic crystal fiber
• Intrinsic Superflat Bands in General Twisted Bilayer Systems
• Truncated atomic plane wave method for the subband structure calculations of Moiré systems
• Gap generation and flat band catalysis in dice model with local interaction
• Twistronics of Kekulé Graphene: Honeycomb and Kagome Flat Bands