Electromagnetic response of composite Dirac fermions in the half-filled Landau level

Hofmann, Johannes

doi:10.1103/physrevb.104.115401

Cited by 6 publications

(8 citation statements)

References 44 publications

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“…To understand the non-equilibrium physics of the energy interconversion process, consider that Hoffmann [104] has recently calculated the electromagnetic response of carriers in the half-filled Landau level. The calculations used the effective field theory proposed for composite fermion by Son [105].…”

Section: Implications Of a Bias-dependent Particle-hole Asymmetrymentioning

confidence: 99%

Kondo resonance effects in emergent flat band materials

Ukpong

2023

Front. Phys.

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Macroscopic degrees of freedom that are involved in the transport of carriers through mesoscopic electronic devices are susceptible to the effects of strong many-body correlations. The presence of magnetic impurities in dilute magnetic alloys typically allow for insights into Kondo effect from the scattering of free carriers by localized electron states of the magnetic impurities but this effect is not well understood when there are no d-band electron states. Herein, the signatures of Kondo resonance effect are elucidated in quantum dots derived from a carbon-nanoline embedded monolayer hexagonal boron nitride whose electron states host flat band ferromagnetism as distinct broken symmetry states. Quantum transport state of mesoscopic devices modelled as quantum dots tunnel coupled to metallic leads is computed by direct diagonalization of the Hamiltonian. The possibility of realizing quantum dots with highly tunable electron states in energy interconversion devices is discussed to show the importance of screening effects on single-electron energy levels. The quantum master equation is solved within different formalisms to determine the stationary-state particle and energy currents. Stability diagrams are calculated to show the dependence of the conductance on experimental control variables of the quantum dot device. The computed responses of the stationary-state transport signatures are used to characterize Kondo resonance effects from flat band states of embedded carbon nanoline-based quantum dots. It is found that the local network structure of the hexagonal ring carbon cluster-based quantum dot has a broken particle-hole symmetry in the transport state. This signals the formation of the quasiparticle states expected in second order scattering when the macroscopic “charge” pseudospin symmetry of the tunnelling electron state is broken dynamically due to charging. The results are discussed to show the implications of a vanishing particle-hole symmetry in the carrier transport state of quantum dots for energy conversion applications.

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Section: Implications Of a Bias-dependent Particle-hole Asymmetrymentioning

confidence: 99%

Kondo resonance effects in emergent flat band materials

Ukpong

2023

Front. Phys.

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“…There are generally oscillatory corrections to ρ yy and ρ xy , however, their amplitudes are typically less prominent and so we concentrate on ∆ρ xx . Finite frequency and wave vector corrections to the formula (III.2)-when the dipole term is present-have been computed by Hofmann [28] in the random phase approximation.…”

Section: Weiss Oscillationsmentioning

confidence: 99%

“…Here, we answer this question in the negative (see Fig. 1), using a composite fermion mean-field theory in which Galilei invariance is preserved to O(|q| 2 ) (see [28] for a related study of electromagnetic response). To this order, the "correction" term is known as the dipole term because it involves a coupling of the composite fermion dipole moment to the external electromagnetic field.…”

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confidence: 99%

Weiss Oscillations and Galilei Invariance

Lu¹,

Kumar²,

Mulligan³

2023

Preprint

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Standard field theoretic formulations of composite fermion theories for the anomalous metals that form at or near even-denominator filling fractions of the lowest Landau level do not possess Galilei invariance. To restore Galilei symmetry, these theories must be supplemented by "correction" terms. We study the effect of the leading "correction" term, known as the dipole term, in the Dirac composite fermion theory (a theory that consists of a Dirac fermion coupled to an Abelian Chern-Simons gauge field) on quantum oscillations in the electrical resistivity due to a periodic scalar potential about even-denominator filling fractions. We find the dipole term to be insufficient to resolve the systematic discrepancy, discovered in [Kamburov et. al., Phys. Rev. Lett. 113, 196801 (2014)], between the locations of the oscillation minima predicted by Dirac composite fermion theory without Galilei invariance and those observed in experiment. Further, in contrast to [Hossain et al., Phys. Rev. B 100, 041112 (2019)], we find the quantum oscillations about the half-filled and quarterfilled lowest Landau level to have qualitatively similar behavior. This analysis uses a mean-field approximation, in which gauge field fluctuations are neglected. Based on this and previous analyses, we speculate the discrepancy with experiment may be an indirect signature of the effect of gauge field fluctuations in composite fermion theory.

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“…In combination, these two modifications lead to response functions consistent with all known symmetries (see, e.g., Ref. [23]).…”

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confidence: 91%

Multiple Magnetorotons and Spectral Sum Rules in Fractional Quantum Hall Systems

Nguyen,

Haldane,

Rezayi

et al. 2021

Preprint

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We study numerically the the charge neutral excitations (magnetorotons) in fractional quantum Hall systems, concentrating on the two Jain states near quarter filling, ν = 2/7 and ν = 2/9, and the ν = 1/4 Fermi-liquid state itself. In contrast to the ν = 1/3 states and the Jain states near half filling, on each of the two Jain states ν = 2/7 and ν = 2/9 the graviton spectral densities show two, instead of one, magnetoroton peaks. The magnetorotons have spin 2 and have opposite chiralities in the ν = 2/7 state and the same chirality in the ν = 2/9 state. We also provide a numerical verification of a sum rule relating the guiding center spin s with the spectral densities of the stress tensor.

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Electromagnetic response of composite Dirac fermions in the half-filled Landau level

Cited by 6 publications

References 44 publications

Kondo resonance effects in emergent flat band materials

Kondo resonance effects in emergent flat band materials

Weiss Oscillations and Galilei Invariance

Multiple Magnetorotons and Spectral Sum Rules in Fractional Quantum Hall Systems

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