Mode conversion and resonant absorption in inhomogeneous materials with flat bands

Kim, Kihong; Kim, Seulong

doi:10.1103/physrevb.105.045136

Cited by 4 publications

(1 citation statement)

References 47 publications

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“…A challenging open problem in artificial lattice systems is the design of conical intersections with higher pseudospin values [4]. Although there have been proposals for generalized conical intersections with arbitrary pseudospin [13,14], and pseudospin-2 ones have been considered theoretically [15,16], no realistic system containing a conical intersection with pseudospin higher than one has been demonstrated until now.…”

Section: Introductionmentioning

confidence: 99%

Pseudospin-2 in photonic chiral borophene

et al. 2023

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Pseudospin is an angular momentum degree of freedom introduced in analogy to the real electron spin in the effective massless Dirac-like equation used to describe wave evolution at conical intersections such as the Dirac cones of graphene. Here, we study a photonic implementation of a chiral borophene allotrope hosting a pseudospin-2 conical intersection in its energy–momentum spectrum. The presence of this fivefold spectral degeneracy gives rise to quasiparticles with pseudospin up to ±2. We report on conical diffraction and pseudospin–orbit interaction of light in photonic chiral borophene, which, as a result of topological charge conversion, leads to the generation of highly charged optical phase vortices.

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Section: Introductionmentioning

confidence: 99%

Pseudospin-2 in photonic chiral borophene

et al. 2023

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Delocalization and re-entrant localization of flat-band states in non-Hermitian disordered lattice models with flat bands

Kim

2022

Progress of Theoretical and Experimental Physics

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We present a numerical study of Anderson localization in disordered non-Hermitian lattice models with flat bands. Specifically we consider one-dimensional stub and two-dimensional kagome lattices that have a random scalar potential and a uniform imaginary vector potential and calculate the spectra of the complex energy, the participation ratio, and the winding number as a function of the strength of the imaginary vector potential, h. The flat-band states are found to show a double transition from localized to delocalized and back to localized states with h, in contrast to the dispersive-band states going through a single delocalization transition. When h is sufficiently small, all flat-band states are localized. As h increases above a certain critical value h1, some pair of flat-band states become delocalized. The participation ratio associated with them increases substantially and their winding numbers become nonzero. As h increases further, more and more flat-band states get delocalized until the fraction of the delocalized states reaches a maximum. For larger h values, a re-entrant localization takes place and, at another critical value h2, all flat-band states return to compact localized states with very small participation ratios and zero winding numbers. This re-entrant localization transition, which is due to the interplay among disorder, non-Hermiticity, and flat band, is a phenomenon occurring in many models having an imaginary vector potential and a flat band simultaneously. We explore the spatial characteristics of the flat-band states by calculating the local density distribution.

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Direct Observation of All-Flat Bands Phononic Metamaterials

Samak,

Bilal

2024

Phys. Rev. Lett.

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Mode conversion and resonant absorption in inhomogeneous materials with flat bands

Cited by 4 publications

References 47 publications

Pseudospin-2 in photonic chiral borophene

Pseudospin-2 in photonic chiral borophene

Delocalization and re-entrant localization of flat-band states in non-Hermitian disordered lattice models with flat bands

Direct Observation of All-Flat Bands Phononic Metamaterials

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