Revisiting excitation gaps in the fractional quantum Hall effect

Abstract

Recent systematic measurements of the quantum well width dependence of the excitation gaps of fractional quantum Hall states in high mobility samples [Villegas Rosales {\it et al.}, Phys. Rev. Lett. {\bf 127}, 056801 (2021)] open the possibility of a better quantitative understanding of this important issue. We present what we believe to be accurate theoretical gaps including the effects of finite width and Landau level (LL) mixing. While theory captures the width dependence, there still remains a deviation between the calculated and the measured gaps, presumably caused by disorder. It is customary to model the experimental gaps of the $n/(2n\pm 1)$ states as ${\Delta }_{n/(2n\pm 1)}=C{e}^2/[(2n\pm 1)\epsilon l]-\Gamma$, where $\epsilon$ is the dielectric constant of the background semiconductor and $l$ is the magnetic length; the first term is interpreted as the cyclotron energy of composite fermions and $\Gamma$ as a disorder-induced broadening of composite-fermion LLs. Fitting the gaps for various fractional quantum Hall states, we find that $\Gamma$ can be nonzero even in the absence of disorder.

6 pages, 7 figures, includes supplemental material

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Cited by in corpus (8)

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• High-Resolution Tunneling Spectroscopy of Fractional Quantum Hall States
• Composite fermion pairing induced by Landau level mixing
• Topological phase transition between composite-fermion and Pfaffian daughter states near ν = 1/2 FQHS
• Taming Landau level mixing in fractional quantum Hall states with deep learning
• Fingerprints of Composite Fermion Lambda Levels in Scanning Tunneling Microscopy
• Unlocking new regimes in fractional quantum Hall effect with quaternions
• The composite fermion theory revisited: a microscopic derivation without Landau level projection