The effect of disorder on integer quantized Hall effect

Gülebağlan, Sinem Erden; Oylumluoglu, Gorkem; Erkaslan, Ugur; Siddiki, A.; Sökmen, I.

doi:10.1016/j.physe.2012.03.017

Cited by 11 publications

(8 citation statements)

References 43 publications

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“…The range of a single impurity would be of the order of few tens of nanometers, however, the potential fluctuations at the overall screened potential might be as large as few microns. A detailed self-consistent calculation regarding the long-range disorder potential fluctuations can be found in the literature2829.…”

Section: Resultsmentioning

confidence: 99%

Anomalous resistance overshoot in the integer quantum Hall effect

Kendirlik

Sirt

Kalkan

et al. 2013

Sci Rep

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In this work we report on experiments performed on smooth edge-narrow Hall bars. The magneto-transport properties of intermediate mobility two-dimensional electron systems are investigated and analyzed within the screening theory of the integer quantized Hall effect. We observe a non-monotonic increase of Hall resistance at the low magnetic field ends of the quantized plateaus, known as the overshoot effect. Unexpectedly, for Hall bars that are defined by shallow chemical etching the overshoot effect becomes more pronounced at elevated temperatures. We observe the overshoot effect at odd and even integer plateaus, which favor a spin independent explanation, in contrast to discussion in the literature. In a second set of the experiments, we investigate the overshoot effect in gate defined Hall bar and explicitly show that the amplitude of the overshoot effect can be directly controlled by gate voltages. We offer a comprehensive explanation based on scattering between evanescent incompressible channels.T he overwhelming interest to utilize quantum mechanics in applied technologies finds one of its first manifestations in the integer quantized Hall effect (IQHE) 1 . The magnetic field dependence of the transport coefficients of a two dimensional electron system (2DES) provides a possibility to standardize resistance in units of the von Klitzing constant h/e 2 , where h is the Planck constant and e is the elementary charge. However, an unexpected non-monotonic magnetic field dependence of the Hall resistance at the low-field-end of the quantized plateaus, known as the overshoot effect, remains a puzzle despite of both theoretical and experimental efforts in various material systems including GaAs/AlGaAs heterostructure 2-6 as well as Si/SiGe 7-13 and Si metal oxide semiconductor field effect transistors 14 . The utilization of the quantized Hall effect as a resistance standard is hindered by such anomalies, especially because their physical mechanism is not well understood. The overshoot effect is observed in these material systems at various filling factors n, defined by the number of occupied quantized (spin resolved) Landau levels (LL) below the Fermi energy. The effect has already been observed in the 1980's, where its physical mechanism was attributed to non-ideal contacts 2-4 , but without providing clear evidence for this hypothesis. Later, the overshoot effect was attributed to the decoupling of the spin-split states within the same LL at odd filling factors by Richter and Wheeler 5 , or, alternatively by the scattering between edge states together with spin-orbit interaction by Komiyama and Nii 6 . Recently, the overshoot effect has been investigated in Si/SiGe heterostructures as a function of current and temperature 12 . These experimental results have been elegantly explained within the screening theory of the integer quantized Hall effect, which explicitly takes into account the direct Coulomb interaction between charge carriers. In this approach the overshoot effect is described using co-existing (curr...

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Section: Resultsmentioning

confidence: 99%

Anomalous resistance overshoot in the integer quantum Hall effect

Kendirlik

Sirt

Kalkan

et al. 2013

Sci Rep

Self Cite

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“…The observed increase of the overshoot with 2DEG density in figure 5 can be explained by two different effects: First, screening of the disorder is improved and thus the probability of electron scattering and tunneling through an IS is reduced 36 . Second, a higher 2DEG density shifts the position of each filling factor or IS to higher magnetic fields and thus higher energy gaps.…”

Section: Discussionmentioning

confidence: 97%

Quantum Hall resistance overshoot in two-dimensional (2D) electron gases: theory and experiment

et al. 2010

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We present a systematical experimental investigation of an unusual transport phenomenon observed in two dimensional electron gases in Si/SiGe heterostructures under integer quantum Hall effect (IQHE) conditions. This phenomenon emerges under specific experimental conditions and in different material systems. It is commonly referred to as Hall resistance overshoot, however, lacks a consistent explanation so far. Based on our experimental findings we are able to develop a model that accounts for all of our observations in the framework of a screening theory for the IQHE. Within this model the origin of the overshoot is attributed to a transport regime where current is confined to co-existing evanescent incompressible strips of different filling factors.

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“…As a result the effect of impurity on the resistance dip is negligible. In one of our recent work [22], we showed that the total potential fluctuates over a spread scale of nearly twohundred nanometers for the high impurity concentration, however the length scale is found to be approximately few micrometers at the low impurity concentration. To unreveal the effect of long-range fluctuations, we also include an external modulation potential to our screening calculations in addition to the confinement potential and investigate the long range disorder potential as well as its effects on the self-consistent potential.…”

Section: Resultsmentioning

confidence: 80%

The dip effect under integer quantized Hall conditions

et al. 2014

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In this work we investigate an unusual transport phenomenon observed in two-dimensional electron gas under integer quantum Hall effect conditions. Our calculations are based on the screening theory, using a semi-analytical model. The transport anomalies are dip and overshoot effects, where the Hall resistance decreases (or increases) unexpectedly at the quantized resistance plateaus intervals. We report on our numerical findings of the dip effect in the Hall resistance, considering GaAs/AlGaAs heterostructures in which we investigated the effect under different experimental conditions. We show that, similar to overshoot, the amplitude of the dip effect is strongly influenced by the edge reconstruction due to electrostatics. It is observed that the steep potential variation close to the physical boundaries of the sample results in narrower incompressible strips, hence, the experimental observation of the dip effect is limited by the properties of these current carrying strips. By performing standard Hall resistance measurements on gate defined narrow samples, we demonstrate that the predictions of the screening theory is in well agreement with our experimental findings. PACS. 73.43.-f Quantum Hall effect -73.43.Cd Theory and modeling -73.43.Fj Novel experimental methods; measurements

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The effect of disorder on integer quantized Hall effect

Cited by 11 publications

References 43 publications

Anomalous resistance overshoot in the integer quantum Hall effect

Anomalous resistance overshoot in the integer quantum Hall effect

Quantum Hall resistance overshoot in two-dimensional (2D) electron gases: theory and experiment

The dip effect under integer quantized Hall conditions

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