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

• Main Authors: Qian, Qi, Nakamura, James R, Fallahi, Saeed, Gardner, Geoffrey C, Watson, John D, Luscher, Silvia, Folk, Joshua A, Csathy, Gabor A, Manfra, Michael J
• Format: Journal Article
• Language: English
• Published: 20.04.2017
• Subjects: Physics - Mesoscale and Nanoscale Physics
• DOI: 10.48550/arxiv.1704.06213

Phys. Rev. B 96, 035309 (2017) 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.