Evanescent incompressible strips as origin of the observed Hall resistance overshoot

Siddiki, A.; Gülebağlan, Sinem Erden; Yurdaşan, N. Boz; Bilgec, G.; Yıldız, Aylin; Sökmen, I.

doi:10.1209/0295-5075/92/67010

Cited by 10 publications

(19 citation statements)

References 23 publications

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“…Hence, for a shallow etched sample, an even edge integer evanescent incompressible strip can co-exist with the odd evanescent incompressible bulk strips. We expect that the disorder is more effective in the large sample, since it offers more long-range potential fluctuations leading to a bulk dominated transport15. We also determined the exact bulk filling factors from the SdH oscillations and checked for the coincidence of the maximum of the overshoot effect and the bulk filling factor.…”

Section: Resultsmentioning

confidence: 99%

“…A detailed theoretical explanation of the overshoot effect within the screening theory is provided in Ref. 12 and 15 taking into account finite size and temperature effects. In particular, Ref.…”

mentioning

confidence: 99%

“…In particular, Ref. 15 specifically predicts that the overshoot effect can be manipulated by changing the electrostatic edge profile of the electron gas, for example by utilizing side gates. In a very recent work, overshoot effect is also predicted for the fractional states and is investigated within the screening theory16.…”

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Anomalous resistance overshoot in the integer quantum Hall effect

Kendirlik

Sirt

Kalkan

et al. 2013

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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%

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Anomalous resistance overshoot in the integer quantum Hall effect

Kendirlik

Sirt

Kalkan

et al. 2013

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“…The main approach [9,11] that has been developed to explain the dip effect phenomenon also relies on the impurity scattering. Shlimak et al found that, this effect can be considered to be a manifestation of the oscillating enhancement of the valley splitting due to the exchange interaction [11], meanwhile in our previous work we found that the overshoot can be well explained within arXiv:1305.4585v1 [cond-mat.mes-hall] 20 May 2013 the self-consistent screening theory [16]. In the later work it is reported that, the overshoot depends strongly on temperature, in contrast, it is immune to short-range impurity scattering and the edge effects are irruptive to the resistance overshoot.…”

Section: Introductionmentioning

confidence: 63%

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 same argument holds also for other filling factors at different field values. Therefore we should not threat incompressible strips as an insulator, since, when W k .λ T 1, the strip is no longer incompressible thermodynamically [20,21,22].…”

Section: Electron Density Profile Incompressible Strips and Capacitamentioning

confidence: 99%

A realistic quantum capacitance model for quantum Hall edge state based Fabry–Pérot interferometers

Kılıcoglu

Eksi

Siddiki

2016

J. Phys.: Condens. Matter

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Abstract.In this work, the classical and the quantum capacitances are calculated for a FabryPérot interferometer operating in the integer quantized Hall regime. We first consider a rotationally symmetric electrostatic confinement potential and obtain the widths and the spatial distribution of the insulating (incompressible) circular strips using a charge density profile stemming from self-consistent calculations. Modelling the electrical circuit of capacitors composed of metallic gates and incompressible/compressible strips, we investigate the conditions to observe Aharonov-Bohm (quantum mechanical phase dependent) and Coulomb Blockade (capacitive coupling dependent) effects reflected in conductance oscillations. In a last step, we solve the Schrödinger and the Poisson equations self-consistently in a numerical manner taking into account realistic experimental geometries. We find that, describing the conductance oscillations either by Aharanov-Bohm or Coulomb Blockade strongly depends on sample properties also other than size, therefore, determining the origin of these oscillations requires further experimental and theoretical investigation.

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Evanescent incompressible strips as origin of the observed Hall resistance overshoot

Cited by 10 publications

References 23 publications

Anomalous resistance overshoot in the integer quantum Hall effect

Anomalous resistance overshoot in the integer quantum Hall effect

The dip effect under integer quantized Hall conditions

A realistic quantum capacitance model for quantum Hall edge state based Fabry–Pérot interferometers

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