Disorder perturbed flat bands: Level density and inverse participation ratio

Shukla, Pragya

doi:10.1103/physrevb.98.054206

Cited by 31 publications

(17 citation statements)

References 68 publications

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“…While an ideal flatband allows the distortion-free storage of compact localized states of tailorable shape, a disorder potential causes distortion and, in the vicinity of intersections (yellow areas), to a coupling into the dispersive band, limiting the state's reliable storage sojourn in the flatband. studies on the impact of perturbations in flatband scenarios [26,[28][29][30][31][32][33][34][35][36][37], e.g., describing the flatband-modified propagation in dispersive bands. We identify and characterize a generic, disorder-induced decay mechanism for flatband states, lifting their static nature and causing their effective diffusion, despite the absence of a kinetic term.…”

Section: Db Fbmentioning

confidence: 99%

Lifetime of flatband states

Gneiting

Nori

2018

Phys. Rev. B

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Flatbands feature the distortion-free storage of compact localized states of tailorable shape. Their reliable storage sojourn is, however, limited by disorder potentials, which generically cause uncontrolled coupling into dispersive bands. We find that, while detuning flatband states from band intersections suppresses their direct decay into dispersive bands, disorder-induced state distortion causes a delayed, dephasing-mediated decay, lifting the static nature of flatband states and setting a finite lifetime for the reliable storage sojourn. We exemplify this generic, disorder-induced decay mechanism at the cross-stitch lattice. Our analysis, which applies platform-independently, relies on the time-resolved treatment of disorder-averaged quantum systems with quantum master equations.

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Section: Db Fbmentioning

confidence: 99%

Lifetime of flatband states

Gneiting

Nori

2018

Phys. Rev. B

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“…At m = γ = 0, the lattice is a standard Lieb lattice and supports a flat band. In the absence of the gain and loss γ = 0, the lattice has a flat band and the band energy is tuned by the coupling strength m [95][96][97][98][99][100][101][102]. The wave transport in the flat band is completely suppressed because of the momentum-independent dispersion relation, leading to a strong localization of the eigenstates.…”

Section: D Non-hermitian Lieb Latticementioning

confidence: 99%

Two-dimensional anisotropic non-Hermitian Lieb lattice

Xie,

Wu,

Zhang

et al. 2021

Preprint

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We study an anisotropic two-dimensional non-Hermitian Lieb lattice, where the staggered gain and loss present in the horizontal and vertical directions, respectively. The intra-cell nonreciprocal coupling generates magnetic flux enclosed in the unit cell of the Lieb lattice and creates nontrivial topology. The active and dissipative topological edge states are along the horizontal and vertical directions, respectively. The two-dimensional non-Hermitian Lieb lattice also supports passive topological corner state. At appropriate magnetic flux, the non-Hermiticity can alter the corner state from one corner to the opposite corner as the non-Hermiticity increases. The gapless phase of the Lieb lattice is characterized by different configurations of exceptional points in the Brillouin zone. The topology of the anisotropic non-Hermitian Lieb lattices can be verified in many experimental platforms including the optical waveguide lattices, photonic crystals, and electronic circuits.

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“…For the modes belonging to the flat band, the particle energy or wave frequency does not depend on the momentum or wave vector and the group velocity vanishes. This has a strong effect on the behavior of quasiparticles and waves and can cause many interesting phenomena by greatly amplifying the effects of various perturbations such as interactions and disorder [4][5][6][7][8][9]. Examples include superconductivity in magic-angle twisted bilayer graphene, flat-band ferromagnetism, and anomalous Landau levels [10][11][12][13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Mode conversion and resonant absorption in inhomogeneous materials with flat bands

Kim,

Kim

2022

Preprint

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Mode conversion of transverse electromagnetic waves into longitudinal oscillations and the associated resonant absorption of wave energy in inhomogeneous plasmas is a phenomenon that has been studied extensively in plasma physics. We show that precisely analogous phenomena occur generically in electronic and photonic systems where dispersionless flat bands and dispersive bands coexist in the presence of an inhomogeneous potential or medium parameter. We demonstrate that the systems described by the pseudospin-1 Dirac equation with two dispersive bands and one flat band display mode conversion and resonant absorption in a very similar manner to p-polarized electromagnetic waves in an unmagnetized plasma by calculating the mode conversion coefficient explicitly using the invariant imbedding method. We also show that a similar mode conversion process takes place in many other systems with a flat band such as pseudospin-2 Dirac systems, continuum models obtained for one-dimensional stub and sawtooth lattices, and two-dimensional electron systems with a quadratic band and a nearly flat band. We discuss some experimental implications of mode conversion in flat-band materials and metamaterials.

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Disorder perturbed flat bands: Level density and inverse participation ratio

Cited by 31 publications

References 68 publications

Lifetime of flatband states

Lifetime of flatband states

Two-dimensional anisotropic non-Hermitian Lieb lattice

Mode conversion and resonant absorption in inhomogeneous materials with flat bands

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