Origin of Pinning Disorder in Magnetic-Field-Induced Wigner Solids

Matthew L. Freeman, P. T. Madathil, L. N. Pfeiffer, K. W. Baldwin, Y. J. Chung, R. Winkler, M. Shayegan, L. W. Engel

Research output: Contribution to journalArticlepeer-review


At low Landau level filling factors (ν), Wigner solid phases of two-dimensional electron systems in GaAs are pinned by disorder and exhibit a pinning mode, whose frequency is a measure of the disorder that pins the Wigner solid. Despite numerous studies spanning the past three decades, the origin of the disorder that causes the pinning and determines the pinning mode frequency remains unknown. Here, we present a study of the pinning mode resonance in the low-ν Wigner solid phases of a series of ultralow-disorder GaAs quantum wells which are similar except for their varying well widths d. The pinning mode frequencies fp decrease strongly as d increases, with the widest well exhibiting fp as low as ≃35 MHz. The amount of reduction of fp with increasing d can be explained remarkably well by tails of the wave function impinging into the alloy-disordered AlxGa1-xAs barriers that contain the electrons. However, it is imperative that the model for the confinement and wave function includes the Coulomb repulsion in the growth direction between the electrons as they occupy the quantum well.

Original languageEnglish (US)
Article number176301
JournalPhysical review letters
Issue number17
StatePublished - Apr 26 2024

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy


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