Abstract

At low Landau level filling factors, 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. This work studies pinning mode resonances in ultralow-disorder GaAs quantum wells with varying well widths and finds that the pinning mode frequency decreases strongly with increasing well width. The trend is explained by wave-function penetration into alloy-disordered AlxGa1−xAs barriers, requiring self-consistent modeling of the confinement and Coulomb repulsion in the growth direction.

Abstract

At low Landau level filling factors, 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. This work studies pinning mode resonances in ultralow-disorder GaAs quantum wells with varying well widths and finds that the pinning mode frequency decreases strongly with increasing well width. The trend is explained by wave-function penetration into alloy-disordered AlxGa1−xAs barriers, requiring self-consistent modeling of the confinement and Coulomb repulsion in the growth direction.

Abstract

At low Landau level filling factors, 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. This work studies pinning mode resonances in ultralow-disorder GaAs quantum wells with varying well widths and finds that the pinning mode frequency decreases strongly with increasing well width. The trend is explained by wave-function penetration into alloy-disordered AlxGa1−xAs barriers, requiring self-consistent modeling of the confinement and Coulomb repulsion in the growth direction.

Abstract

At low Landau level filling factors, 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. This work studies pinning mode resonances in ultralow-disorder GaAs quantum wells with varying well widths and finds that the pinning mode frequency decreases strongly with increasing well width. The trend is explained by wave-function penetration into alloy-disordered AlxGa1−xAs barriers, requiring self-consistent modeling of the confinement and Coulomb repulsion in the growth direction.