Conditions for experimental observation of the critical behavior of the longitudinal and Hall resistance in the quantum Hall regime in gallium and indium arsenide-based heterostructures

We have investigated transport properties in high magnetic field of a gated two-dimensional electron system (2DES) separated by a thin barrier from a layer of self-assembled InAs quantum dots (QDs) in the quantum Hall regime. The quality of 2DES was found to be high enough to observe both integer and fractional quantum Hall effect (QHE), despite the proximity of the QD layer to the 2DES. However, significant suppression of the magnetoresistance (ρ xx ) and Hall resistance (ρ xy ) were observed in higher magnetic field range of filling factor ν < 1 when a positive voltage was applied to the front gate. The gate voltage dependence of ρ xx and ρ xy shows a well-defined hysteresis loop at the narrow gate voltage range between -0.2 and +0.2 V at ν < 1, while no anomaly was observed at ν > 1. We deduce that charging and discharging of QDs occurs when the gate voltage is varied around Vg ~ 0 V, which indicates that the electron charge states of the QDs affect the transport properties of the nearby 2DES only at ν < 1. We infer that the spin-flip process induces a non-equilibrium state in the 2DEG, which causes the suppression of ρ xx and ρ xy .

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GRAPHENE IN THE QUANTUM HALL REGIME: EFFECTS OF VACANCIES, SUBLATTICE POLARIZATION AND DISORDER

International Journal of Modern Physics B ◽

10.1142/s0217979209062086 ◽

2009 ◽

Vol 23 (12n13) ◽

pp. 2618-2627 ◽

Cited By ~ 2

Author(s):

ANA L. C. PEREIRA ◽

PETER A. SCHULZ

Keyword(s):

Quantum Hall ◽

Tight Binding ◽

Wave Functions ◽

Hall Resistance ◽

Monolayer Graphene ◽

Binding Model ◽

Quantum Hall Regime ◽

Hall Regime ◽

Valley Polarization ◽

Disorder Effect

We investigate the effects of vacancies, disorder and sublattice polarization on the electronic properties of a monolayer graphene in the quantum Hall regime. Energy spectra as a function of magnetic field and the localization properties of the states within the graphene Landau levels (LLs) are calculated through a tight-binding model. We first discuss our results considering vacancies in the lattice, where we show that vacancies introduce extra levels (or well-defined bands) between consecutive LLs. An striking consequence here is that extra Hall resistance plateaus are expected to emerge when an organized vacancy superlattice is considered. Secondly, we discuss the anomalous localization properties we have found for the lowest LL, where an increasing disorder is shown to enhance the wave functions delocalization (instead of inducing localization). This unexpected effect is shown to be directly related to the way disorder increasingly destroys the sublattice (valley) polarization of the states in the lowest LL. The reason why this anomalous disorder effect occurs only for the zero-energy LL is that, in absence of disorder, only for this level all the states are sublattice polarized, i.e., their wave functions have amplitudes in only one of the sublattices.

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Hall resistance anomalies in the integer and fractional quantum Hall regime

Physical Review B ◽

10.1103/physrevb.102.115306 ◽

2020 ◽

Vol 102 (11) ◽

Author(s):

E. Peraticos ◽

S. Kumar ◽

M. Pepper ◽

A. Siddiki ◽

I. Farrer ◽

...

Keyword(s):

Quantum Hall ◽

Hall Resistance ◽

Fractional Quantum ◽

Fractional Quantum Hall ◽

Quantum Hall Regime ◽

Hall Regime

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ANOMALOUS QUANTUM HALL RESISTANCE IN Al0.6Ga0.4As0.1Sb0.9/InAs QUANTUM WELL WITH TUNABLE CARRIER DENSITY

International Journal of Modern Physics B ◽

10.1142/s0217979207042938 ◽

2007 ◽

Vol 21 (08n09) ◽

pp. 1419-1423

Author(s):

K. OTO ◽

S. TAMIYA ◽

S. ISHIDA ◽

A. OKAMOTO ◽

I. SHIBASAKI

Keyword(s):

Quantum Well ◽

Carrier Transport ◽

Chemical Potential ◽

Lattice Mismatch ◽

Quantum Hall ◽

Hall Resistance ◽

Persistent Photoconductivity ◽

Quantum Hall Regime ◽

Hall Regime ◽

Magneto Resistance

We have investigated magneto-resistance in InAs/Al 0.6 Ga 0.4 As 0.1 Sb 0.9 quantum well (QW), where the lattice mismatch at the interface is less than 2 %. The carrier concentration can be tuned by using positive and negative persistent photoconductivity effect, selected by the wavelength (λ=1.6μ m or 0.95 μm) of illumination. The electrons and holes coexist in the QW structure, and the contribution of both carriers should be taken into account. The observed deviation of Hall plateaus from the quantized value can be understood by considering the carrier transport in both electron and hole edge channels, and the equilibrium of chemical potential at the all electrodes in the sample. The transport properties in quantum Hall regime measured in the samples with the QW thickness of 15, 50 and 150 nm are reported.

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