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Disorder effects in two-dimensional flat-band system with next-nearest-neighbor hopping

2026/01/16 by Yue Heng Liu, Zi-Xiang Hu, Qi Li
Physics and Astronomy · #Action (physics) #Component (thermodynamics) #Focus (optics) #Noise (video) #Nonlinear Photonic Systems #Quantum and electron transport phenomena #Semiconductor Quantum Structures and Devices

paper · pdf · doi:10.1103/lm27-ktjh

openalex publication_date 2026/06/26 · openalex created_date 2026/06/27 · openalex updated_date 2026/08/05

Abstract

For two-dimensional Lieb lattice, while intrinsic spin-orbit coupling is responsible for opening the gap that exhibits the quantum spin Hall effect, topological phase transitions are driven by a real next-nearest-neighbor (NNN) hopping. In this work, we utilize the transfer matrix method to study the flat-band localization mechanism in the presence of complex NNN hoppings. We demonstrate that the geometric localization in flat bands can be alleviated by topological edge states under weak disorder. Furthermore, correlated disorders are shown to induce inverse Anderson transition with the topological edge states persisting under strong disorder, a robustness confirmed by Chern number calculations, which identifies the root cause of this phenomenon. These findings establish a unified platform for investigating topological phase transitions, flat bands, and disorder effects.

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