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arXiv · 1704.06213

Quantum Lifetime in Ultra-High Quality GaAs Quantum Wells: Relationship to $\Delta_{5/2}$ and Impact of Density Fluctuations

Qi Qian·James R. Nakamura·Saeed Fallahi·Geoffrey C. Gardner·John D. Watson·Silvia Luscher·Joshua A. Folk·Gabor A. Csathy·Michael J. Manfra
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Abstract

We consider quantum lifetime derived from low-field Shubnikov-de Haas oscillations as a metric of quality of the two-dimensional electron gas in GaAs quantum wells that expresses large excitation gaps in the fractional quantum Hall states of the N=1 Landau level. Analysis indicates two salient features: 1) small density inhomogeneities dramatically impact the amplitude of Shubnikov-de Haas oscillations such that the canonical method (cf. Coleridge, Phys. Rev. B \textbf{44}, 3793) for determination of quantum lifetime substantially underestimates $\tau_q$ unless density inhomogeneity is explicitly considered; 2) $\tau_q$ does not correlate well with quality as measured by $\Delta_{5/2}$, the excitation gap of the fractional quantum Hall state at 5/2 filling.

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Qi Qian, James R. Nakamura, Saeed Fallahi, Geoffrey C. Gardner, John D. Watson, Silvia Luscher, Joshua A. Folk, Gabor A. Csathy, Michael J. Manfra. 2017-04-20. Quantum Lifetime in Ultra-High Quality GaAs Quantum Wells: Relationship to $\Delta_{5/2}$ and Impact of Density Fluctuations. https://doi.org/10.1103/physrevb.96.035309

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