Electrostatic potential and quantum transport in a one-dimensional channel of an induced two-dimensional electron gas

Ткаченко, О. А.; Ткаченко, В. А.; Baksheyev, D. G.; Pyshkin, K. S.; Harrell, R. H.; Linfield, E. H.; Ritchie, D. A.; Ford, C. J. B.

doi:10.1063/1.1352024

Cited by 34 publications

(30 citation statements)

References 16 publications

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“…To do so we use the recursive Green's function method 30,31 which is efficient for calculation of single particle 27 . We consider a "sample" of approximately 6µm × 6µm size.…”

Section: F Recursive Green's Functions and Conductancementioning

confidence: 99%

Effects of Coulomb screening and disorder on an artificial graphene based on nanopatterned semiconductor

Ткаченко

Terekhov

et al. 2015

2D Mater.

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A residual disorder in the gate system is the main problem on the way to create artificial graphene based on two-dimensional electron gas. The disorder can be significantly screened/reduced due to the many-body effects. To analyse the screening/disorder problem we consider AlGaAs/GaAs/AlGaAs heterostructure with two metallic gates. We demonstrate that the design least susceptible to the disorder corresponds to the weak coupling regime (opposite to tight binding) which is realised via system of quantum anti-dots. The most relevant type of disorder is the area disorder which is a random variation of areas of quantum anti-dots. The area disorder results in formation of puddles. Other types of disorder, the position disorder and the shape disorder, are practically irrelevant. The formation/importance of puddles dramatically depends on parameters of the nanopatterned heterostructure. A variation of the parameters by 20-30% can change the relative amplitude of puddles by orders of magnitude. Based on this analysis we formulate criteria for the acceptable design of the heterostructure aimed at creation of the artificial graphene.

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“…To do so we use the recursive Green's function method 30,31 which is efficient for calculation of single particle 27 . We consider a "sample" of approximately 6µm × 6µm size.…”

Section: F Recursive Green's Functions and Conductancementioning

confidence: 99%

Effects of Coulomb screening and disorder on an artificial graphene based on nanopatterned semiconductor

Ткаченко

Terekhov

et al. 2015

2D Mater.

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“…This implies that U (y) depends on n. The self-consistent potential U (x, y) for our device is calculated in Section C of the supplementary material using the Thomas-Fermi-Poisson method, see Refs. [23][24][25]. The potentials U (y) = U (x = 0, y) for n = 1, 3, 5, 8 are plotted in Fig.3a.…”

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confidence: 99%

Mechanisms for Strong Anisotropy of In-Plane g -Factors in Hole Based Quantum Point Contacts

et al. 2017

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In-plane hole g-factors measured in quantum point contacts based on p-type heterostructures strongly depend on the orientation of the magnetic field with respect to the electric current. This effect, first reported a decade ago and confirmed in a number of publications, has remained an open problem. In this work, we present systematic experimental studies to disentangle different mechanisms contributing to the effect and develop the theory which describes it successfully. We show that there is a new mechanism for the anisotropy related to the existence of an additional B+k 4 − σ+ effective Zeeman interaction for holes, which is kinematically different from the standard single Zeeman term B−k 2 − σ+ considered until now.PACS numbers: 71.70. Ej, 73.22.Dj, 71.18.+y A quantum point contact (QPC) is a narrow quasione-dimensional (1D) constriction linking two twodimensional (2D) electron or hole reservoirs. Experimental studies of QPCs started with the discovery of the conductance quantization in steps of. The steps are due to the quantization of transverse channels [3]. Effects of many-body correlations in QPCs were identified by a "0.7-anomaly" in the conductance, an enhancement of the g-factor in the 1D limit [4], and by a zero bias anomaly [5]. G-factors in n-type QPCs have been measured in numerous experiments; a relatively recent one is reported in Ref. [6].The in-plane electron g-factor in a QPC takes the same value for any direction of the in-plane magnetic field. Even in InGaAs, which has appreciable spin-orbit coupling, no in-plane g-factor anisotropy has been observed [7]. Contrary to this, measurements for holes in QPCs based on GaAs p-type heterostructures indicate a huge anisotropy. All previously reported values of the g-factor for magnetic fields applied perpendicular to the QPC are consistent with g ⊥ = 0 within experimental error, while the g-factor g || for the parallel direction is nonzero [8][9][10].Regardless of numerous studies, the g-factor anisotropy effect in QPCs remains unclear.One mechanism to explain the g-factor anisotropy was suggested in Ref. [9]. This mechanism is based on the crystal anisotropy of the cubic lattice. While it is not negligible, the contribution of this mechanism is too small to explain the observed anisotropy.In this work, we identify a new mechanism for the g-factor anisotropy unrelated to the crystal lattice. It is instructive to use classification in powers of crystal anisotropy η defined below. The new mechanism is leading in η and the mechanism [9] is subleading. The new mechanism is negligible at very low hole densities. However, at real physical densities it is the major anisotropy mechanism. Previous measurements were performed in 2D hole systems formed at a single heterojunction [8, 9], which can be modeled as a triangular potential well. There is also a measurement with an asymmetric quantum well [10] which can be modeled as a square potential with an electric field along the z-axis. The z-axis is perpendicular to the plane of the 2D hole system. The z-as...

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“…This form is quite appropriate for simulation of short ballistic channels, including escape to two-dimensional reservoirs. 3,4 This potential does not yield any features in the transmittance D(E) except the steps of unit height. 32 The values of the parameters were taken to be typical for ballistic quantum wires in a GaAs/AlGaAs two-dimensional electron gas.…”

Section: Calculation Of 1d Electron Densitymentioning

confidence: 96%

“…[2][3][4][5] The same approach explains the alternation of zero plateaux and peaks of thermopower (Seebeck coefficient S), which obeys the Mott formula, S M ∝ ∂ ln G(V g , T )/∂E F . [6][7][8][9][10] However, the dependence G(V g ) of the conductance on the gate voltage exhibits a narrow region of anomalous behavior, the 0.7 · 2e 2 /h plateau.…”

Section: Intoductionmentioning

confidence: 99%

“…In the experiment, on the contrary, the gate voltage V g is varied independently and, according to the electrostatic calculation (see Appendix B and Refs. 4,5), there is a linear relation between n c and V g above some small n c0 value, so that the temperature dependence of n c (V g ) can be neglected. According to Fig.…”

Section: Calculation Of 1d Electron Densitymentioning

confidence: 99%

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Temperature dependence of conductance and thermopower anomalies of quantum point contacts

Ткаченко

2013

Jetp Lett.

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It has been shown within the Landauer single-channel approach that the presence of the 0.7 anomaly in the conductance of a ballistic microcontact and the respective plateau in the thermopower implies unusual pinning of the potential barrier height U at a depth of kBT below the Fermi level EF . A simple way of taking into account the effect of electron-electron interaction on the profile and temperature dependence of a smooth onedimensional potential barrier in the lower spin degeneracy subband of the microcontact has been proposed. The calculated temperature dependences of the conductance and Seebeck coefficient agree with the experimental gate-voltage dependences, including the emergence of anomalous plateaux with an increase in temperature.

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Electrostatic potential and quantum transport in a one-dimensional channel of an induced two-dimensional electron gas

Cited by 34 publications

References 16 publications

Effects of Coulomb screening and disorder on an artificial graphene based on nanopatterned semiconductor

Effects of Coulomb screening and disorder on an artificial graphene based on nanopatterned semiconductor

Mechanisms for Strong Anisotropy of In-Plane g -Factors in Hole Based Quantum Point Contacts

Temperature dependence of conductance and thermopower anomalies of quantum point contacts

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