Novel magneto-optical behavior in the Wigner-solid regime

Buhmann, H.; Joss, W.; K, von Klitzing; Kukushkin,; Plaut, A. S.; Martinez, G.; Vb, Timofeev

doi:10.1103/physrevlett.66.926

Cited by 192 publications

(88 citation statements)

References 12 publications

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“…The insulator is understood as a form of Wigner solid [2][3][4][5][6][7][8][9][10][11][12][13][14] , a state of matter composed of charge carriers arranged to minimize their mutual repulsion while constrained to a fixed density by charge neutrality. The role of the disorder is crucial in producing the insulating behavior, since the Wigner solid is necessarily pinned by any disorder.…”

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confidence: 99%

Pinning modes of high-magnetic-field Wigner solids with controlled alloy disorder

et al. 2014

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For a series of samples with 2D electron systems in dilute Al x Ga 1−x As, with varying x from 0 to 0.8%, we survey the pinning mode resonances of Wigner solids at the low Landau filling termination of the fractional quantum Hall effect (FQHE) series. For all x studied, the pinning modes are present with frequencies, f pk , that are consistent with collective weak pinning. For x ≥ 0.22% we find f pk vs B exhibits a rapid increase that is not present for x = 0. We find the observed f pk is much smaller than values calculated with a simple Wigner solid model which neglects the effects of the disorder on the charge distribution of a carrier.1 arXiv:1401.3912v1 [cond-mat.mes-hall] 16 Jan 2014In two-dimensional electron systems (2DES) hosted in GaAs an insulating phase occurs at the low Landau filling factor (ν) termination of the fractional quantum Hall effect (FQHE) 1 series. The insulator is understood as a form of Wigner solid 2-14 , a state of matter composed of charge carriers arranged to minimize their mutual repulsion while constrained to a fixed density by charge neutrality. The role of the disorder is crucial in producing the insulating behavior, since the Wigner solid is necessarily pinned by any disorder.The spectra of the low ν insulating phases of 2DES exhibit a microwave or rf resonance 6-9,12,13 that is identified as a pinning mode 7,9,[12][13][14][15] , in which pieces of the solid oscillate collectively about their pinned positions. This disorder-induced mode is a powerful tool for study of solid phases in 2DES, which occur under many conditions 14 besides the low ν insulator. But a detailed understanding of how the solid phase is pinned is lacking.The frequency, f pk , of the resonance has been qualitatively found to increase with increasing accidental disorder, as roughly characterized by the mobilities of a variety of samples, but there is no systematic experimental knowledge of the relationship between the disorder characteristics and the pinning mode, and no microscopic picture of the solid in the presence of disorder.This paper presents pinning mode measurements of the low ν insulator in a series of samples with quantifiable, controlled alloy disorder, produced by using a dilute Al alloy, Al x Ga 1−x As, as the channel in which the 2DES resides. The characteristics of these samples have been well established in earlier work on these wafers [16][17][18][19][20] . In particular, study 16 of the mobility vs x has shown that for x ≤ 0.85% the Al is randomly distributed in the channel, and has allowed modeling the potential around each Al atom as a spherical square well with known radius and potential-depth parameters. Relevant for high magnetic field (B) studies, both this radius and the typical Al spacing in three dimensions are much less than the magnetic length, l B , for all nonzero x that we studied, and for any accessible B. The samples we studied with x > 0 had ∼ 10 2 to 10 3 Al within the typical volume of a carrier.An important aspect of the disorder in 2DES in high B is its effe...

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Pinning modes of high-magnetic-field Wigner solids with controlled alloy disorder

et al. 2014

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“…Because of the correlated nature of the FQHE, the insulating states above and below the FQHE states at ν = 1/3 and 1/5 are expected to be driven by electronelectron correlation rather than disorder, enhancing the likelihood of formation of a Wigner crystal. This has given impetus for various electrical, acoustic, microwave, and optical investigations of the high field insulating phases [7,8,9,10,11,12,13,14,15].…”

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Vertical confinement and evolution of reentrant insulating transition in the fractional quantum Hall regime

Yang¹,

Kang²,

Hannahs³

et al. 2003

Phys. Rev. B

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We have observed an anomalous shift of the high field reentrant insulating phases in a twodimensional electron system (2DES) tightly confined within a narrow GaAs/AlGaAs quantum well. Instead of the well-known transitions into the high field insulating states centered around ν = 1/5, the 2DES confined within an 80Å-wide quantum well exhibits the transition at ν = 1/3.Comparably large quantum lifetime of the 2DES in narrow well discounts the effect of disorder and points to confinement as the primary driving force behind the evolution of the reentrant transition.

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“…(945) to be an electron solid (Wigner crystal). The Wigner transition was observed in nearly perfect GaAlAs/GaAs heterostructures [1][2][3][4][5], and quite recently in the InGaAs/ΙnΡ heterostructure too [6,7]. In GaAIAs/GaAs the value of the critical filling factor v at T = 0 K, below which Wigner crystallization occurs, was about 0.2 [1,2,4] and 0.28 [3], while in InGaAs/InP a higher value of about νc = 0.49 was obtained [7].…”

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confidence: 99%

Activated Transport in Magnetic-Field Induced Insulating Phase in Two-Dimensional Electron Gas in InGaAs/InP Heterostructures

et al. 1997

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Novel magneto-optical behavior in the Wigner-solid regime

Cited by 192 publications

References 12 publications

Pinning modes of high-magnetic-field Wigner solids with controlled alloy disorder

Pinning modes of high-magnetic-field Wigner solids with controlled alloy disorder

Vertical confinement and evolution of reentrant insulating transition in the fractional quantum Hall regime

Activated Transport in Magnetic-Field Induced Insulating Phase in Two-Dimensional Electron Gas in InGaAs/InP Heterostructures

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