Unusual Landau level pinning and correlated<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>ν</mml:mi><mml:mo>=</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:math>quantum Hall effect in hole systems confined to wide GaAs quantum wells

Liu, Yang; Hasdemir, S.; Shayegan, M.; Pfeiffer, L. N.; West, K. W.; Baldwin, K. W.

doi:10.1103/physrevb.92.195156

Cited by 8 publications

(4 citation statements)

References 24 publications

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“…A very small g-factor was also achieved in an Al 0.13 Ga 0.87 As/GaAs quantum well (QW) structure leading to a Skyrmionic excitation composed of approximately 50 spins [15]. Another possibility to obtain a vanishing E Z is to exploit LL crossings in a 2DHG, which occur at finite magnetic field due to heavy-and light-hole mixing in the valence band [16][17][18][19][20][21][22][23]. In this scenario, an interesting so far unresolved question, is the robustness of the QHF and the role of Skyrmions at the LL crossing.…”

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confidence: 99%

Spin Reversal of a Quantum Hall Ferromagnet at a Landau Level Crossing

et al. 2020

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When Landau levels (LLs) become degenerate near the Fermi energy in the quantum Hall regime, interaction effects can drastically modify the electronic ground state. We study the quantum Hall ferromagnet formed in a two-dimensional hole gas around the LL filling factor ν ¼ 1 in the vicinity of a LL crossing in the heave-hole valence band. Cavity spectroscopy in the strong-coupling regime allows us to optically extract the spin polarization of the two-dimensional hole gas. By analyzing this polarization as a function of hole density and magnetic field, we observe a spin flip of the ferromagnet. Furthermore, the depolarization away from ν ¼ 1 accelerates close to the LL crossing. This is indicative of an increase in the size of skyrmion excitations as the effective Zeeman energy vanishes at the LL crossing.

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confidence: 99%

Spin Reversal of a Quantum Hall Ferromagnet at a Landau Level Crossing

et al. 2020

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“…1(d)). The crossing is signaled by a profound weakening of the ν = 1 integer QHS at intermediate θ [16,17]. As is evident in Fig.…”

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confidence: 57%

“…The results we report here attest to the extremely rich physics of 2DHSs confined to wide GaAs QWs. In these systems one can cause a crossing of the lowest two LLs by either changing the density [44] or titling the sample in magnetic field [16,17,44]. Depending on the sample parameters, the crossing can destroy the ordinary QHSs, both at integer and fractional fillings, and bring to life unusual phases such as a FQHS at ν = 1/2 [44] or, as we have shown here, an anisotropic IP signaling a twocomponent, striped Wigner crystal.…”

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confidence: 84%

Observation of an Anisotropic Wigner Crystal

et al. 2016

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We report a new correlated phase of two-dimensional charged carriers in high magnetic fields, manifested by an anisotropic insulating behavior at low temperatures. It appears in a large range of low Landau level fillings 1/3≲ν≲2/3 in hole systems confined to wide GaAs quantum wells when the sample is tilted in magnetic field to an intermediate angle. The parallel field component (B_{∥}) leads to a crossing of the lowest two Landau levels, and an elongated hole wave function in the direction of B_{∥}. Under these conditions, the in-plane resistance exhibits an insulating behavior, with the resistance along B_{∥} about 10 times smaller than the resistance perpendicular to B_{∥}. We interpret this anisotropic insulating phase as a two-component, striped Wigner crystal.

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“…The first crossing occurs between two LLs that have opposite pseudo-spin characters, while the second crossing involves a LL which emanates from an upper (excited) subband. The second crossing is re-markable on its own and entails very unusual evolutions of the ground state both at ν = 1 [45,46] as well as at ν = 1/2 where an even-denominator fractional QH liquid state [47], or an anisotropic, pinned Wigner solid state [48] can emerge. The details of the first crossing, which is the subject of our investigation here, are less known [49].…”

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Robust Quantum Hall Ferromagnetism near a Gate-Tuned ν = 1 Landau Level Crossing

Ma,

Wang,

Chung

et al. 2022

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In a low-disorder two-dimensional electron system, when two Landau levels of opposite spin or pseudo-spin cross at the Fermi level, the dominance of the exchange energy can lead to a ferromagnetic, quantum Hall ground state whose gap is determined by the exchange energy and has skyrmions as its excitations. This is normally achieved via applying either hydrostatic pressure or uniaxial strain. We study here a very high-quality, low-density, two-dimensional hole system, confined to a 30-nm-wide (001) GaAs quantum well, in which the two lowest-energy Landau levels can be gate tuned to cross at and near filling factor ν = 1. As we tune the field position of the crossing from one side of ν = 1 to the other by changing the hole density, the energy gap for the quantum Hall state at ν = 1 remains exceptionally large, and only shows a small dip near the crossing. The gap overall follows a √ B dependence, expected for the exchange energy. Our data are consistent with a robust quantum Hall ferromagnet as the ground state.

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Unusual Landau level pinning and correlatedν=1quantum Hall effect in hole systems confined to wide GaAs quantum wells

Cited by 8 publications

References 24 publications

Spin Reversal of a Quantum Hall Ferromagnet at a Landau Level Crossing

Spin Reversal of a Quantum Hall Ferromagnet at a Landau Level Crossing

Observation of an Anisotropic Wigner Crystal

Robust Quantum Hall Ferromagnetism near a Gate-Tuned ν = 1 Landau Level Crossing

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