Current-induced asymmetries of incompressible strips in narrow quantum Hall systems

Gerhardts, Rolf R.; Πανοσ, Κωνσταντινοσ; Weis, J.

doi:10.1088/1367-2630/15/7/073034

Cited by 15 publications

(31 citation statements)

References 17 publications

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“…Incompressible and compressible regions appear in the 2DES under high magnetic field due to electrostatic screening of superposed electrostatic potential variations, which are naturally present, especially towards the 2DES edges. Transport calculations taking such screening into account and assuming local equilibrium in stationary non-equilibrium states [14][15][16][17][18] show good agreement with the experimental findings. Moreover, Güven et al [14] also analyzed the Hall potential profiles for higher bias and predicted, for the regime with current near the edges, an asymmetric current distribution at both edges accompanied by different widths of the incompressible stripes carrying the current.…”

Section: Introductionsupporting

confidence: 65%

Current distribution and Hall potential landscape towards breakdown of the quantum Hall effect: a scanning force microscopy investigation

et al. 2014

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We present line-and area-scans of the Hall potential landscape of a twodimensional electron system (2DES) in narrow (AlGa)As-based Hall bars under quantum Hall (QH) conditions, obtained by low-temperature scanning force microscopy. For several magnetic field values B in the regime of the QH plateau with Landau level filling factor ν = 2, we measured the evolution of the Hall potential profiles and of the longitudinal voltage drop along the Hall bar as a function of increasing voltage/current bias, leading finally to the electrically induced breakdown of the quantum Hall effect (QHE). Basically two types of evolution were observed: for the low B-field side of the QHE plateau, two distinct Hall potential drops appear close to the two edges of a cross section, equally distributed at low bias but continuously developing to an asymmetrical distribution with increasing bias. At high bias, a steady increase of the longitudinal voltage drop is observed, accompanied by a rising slope of the Hall potential drop in the bulk. For the upper B-field side of the QH plateau, the Hall voltage drops are broadly distributed across the whole cross section, and the distribution remains almost unchanged until the bias reaches a critical value where the Hall potential profile changes rather abruptly, enhancing locally the Hall field. Beyond this, with further increase of the bias, a steep rise of the longitudinal voltage drop is detected. These findings are naturally explained in the microscopic picture of the QHE, based on the self-consistent evolution of the Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. compressible and incompressible landscape inside the 2DES with increasing bias.Keywords: quantum Hall effect, breakdown of the QHE, incompressible stripes, scanning force microscopy, current distribution, Hall potential landscape 1 Layer sequence for sample A: on top of a semi-insulating GaAs substrate, a GaAs/AlGaAs superlattice 50x (10 nm, 10 nm) was grown, followed by 500 nm GaAs, 20 nm AlGaAs spacer, 25 nm AlGaAs doped with Si, 5 nm AlGaAs, and, finally, 5 nm GaAs as cap layer. For sample B, the AlGaAs spacer layer was 25 nm thick, the AlGaAs:Si doping layer 20 nm. 2 New J. Phys. 16 (2014) 113071 K Panos et al

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Section: Introductionsupporting

confidence: 65%

Current distribution and Hall potential landscape towards breakdown of the quantum Hall effect: a scanning force microscopy investigation

et al. 2014

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“…These calculations revealed a strongly nonlinear response behavior under the conditions of the IQHE, with a current-induced asymmetry between the ISs near opposite sample edges. These asymmetries were nicely confirmed by experiments [5,13] using unidirectional currents of different strengths. For sufficiently strong current, a breakdown of the IQHE was observed, which occurred as a continuous increase of the voltage drop inside the sample with increasing strength of the applied bias voltage, i.e.…”

Section: Introductionsupporting

confidence: 61%

“…This experimental situation can be simulated sufficiently well by the simple model of a relatively narrow (width 3 μm), translation-invariant Hall bar with a constant density of positive background charges, defining a confinement potential, which leads to an electron density profile decreasing monotonically from the center towards the edges of the bar. As B is increased towards the high-B part of the QHP, in this model the ISs become wider and move towards the center of the sample, so that the ASDC flows only through a narrow region in the middle of the Hall bar [13]. In the experiment, on the other hand, the high-B part of the QHP is 'bulk-dominated', since the ASDC is distributed over a wide region of the bulk of the Hall bar [5].…”

Section: Introductionmentioning

confidence: 99%

Current distribution in narrow translation-invariant quantum-Hall-systems with lateral density modulation

Gerhardts

2019

New J. Phys.

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A previously developed self-consistent screening and magneto-transport theory for laterally confined, translation-invariant quantum-Hall-systems is applied to two-dimensional electron systems created by a donor sheet with a lateral density modulation. The previous calculations, assuming a homogeneous donor charge density, could explain experimental results on the spatial distribution of an applied source-drain-current, and the resulting Hall potential, only for the 'edge-dominated' low-magnetic-field part of a quantum-Hall-plateau, where the current flows through incompressible stripes near the edges. For the high-magnetic-field regime of the plateau, they predicted current flow only in a narrow stripe in the center of the sample, whereas the experiments found current in a wide region of its bulk. Assuming a suitably modulated donor charge density, we can avoid this discrepancy, and we obtain a strong dependence of the distribution of the applied current on magnetic field, lattice temperature, and the current-strength.

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“…Finally, we extended our models to account for the effects of quadrupolar splitting of nuclear levels and also depict the electronic transport signatures that arise from single and multi-photon processes. We believe that this work sets stage for a more rigorous approach which will include a self-consistent solution of the potential profile [45][46][47][48][49][50][51][52][53][54][55] of the channel along with the spatial distribution the nuclear spin profile. In this section, we show that the rate of spin-flip scattering from the forward propagating up-spin (down-spin) channel originating in the source contact to the forward propagating down-spin (up-spin) channel terminating in the drain contact per unit energy at the QPC can indeed be approximated by a transmission coefficient that is dependent on the nuclear polarization.…”

Section: Discussionmentioning

confidence: 99%

Landauer-Büttiker approach for hyperfine mediated electronic transport in the integer quantum Hall regime

et al. 2017

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The interplay of spin-polarized electronic edge states with the dynamics of the host nuclei in quantum Hall systems presents rich and non-trivial transport physics. Here, we develop a LandauerBüttiker approach to understand various experimental features observed in the integer quantum Hall set ups featuring quantum point contacts. The approach developed here entails a phenomenological description of spin resolved inter-edge scattering induced via hyperfine assisted electron-nuclear spin flip-flop processes. A self-consistent simulation framework between the nuclear spin dynamics and edge state electronic transport is presented in order to gain crucial insights into the dynamic nuclear polarization effects on electronic transport and in turn the electron-spin polarization effects on the nuclear spin dynamics. In particular, we show that the hysteresis noted experimentally in the conductance-voltage trace as well as in the resistively detected NMR lineshape results from a lack of quasi-equilibrium between electronic transport and nuclear polarization evolution. In addition, we present circuit models to emulate such hyperfine mediated transport effects to further facilitate a clear understanding of the electronic transport processes occurring around the quantum point contact. Finally, we extend our model to account for the effects of quadrupolar splitting of nuclear levels and also depict the electronic transport signatures that arise from single and multi-photon processes.

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Current-induced asymmetries of incompressible strips in narrow quantum Hall systems

Cited by 15 publications

References 17 publications

Current distribution and Hall potential landscape towards breakdown of the quantum Hall effect: a scanning force microscopy investigation

Current distribution and Hall potential landscape towards breakdown of the quantum Hall effect: a scanning force microscopy investigation

Current distribution in narrow translation-invariant quantum-Hall-systems with lateral density modulation

Landauer-Büttiker approach for hyperfine mediated electronic transport in the integer quantum Hall regime

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