S. Aktas

Theoretical investigation of the electron velocity in quantum Hall bars, in the out of linear response regime

Abstract We report on our theoretical investigation of the electron velocity in (narrow) quantum Hall systems, considering the out-of-linear-response regime. The electrostatic properties of the electron system are obtained by the Thomas–Fermi–Poisson nonlinear screening theory. The electron velocity distribution as a function of the lateral coordinate is obtained from the slope of the screened potential within the incompressible strips (ISs). The asymmetry induced by the imposed current on the ISs is investigated, as a function of the current intensity and impurity concentration. We find that the width of the IS on one side of the sample increases linearly with the intensity of the applied current and decreases with the impurity concentration.

The current polarization rectification of the integer quantized Hall effect

Abstract We report on our theoretical investigation considering the widths of quantized Hall plateaus (QHPs) depending on the density asymmetry induced by the large current within the out-of-linear response regime. We solve the Schrodinger equation within the Hartree type mean field approximation using Thomas–Fermi–Poisson nonlinear screening theory. We observe that the two-dimensional electron system splits into compressible and incompressible regions for certain magnetic field intervals, where the Hall resistance is quantized and the longitudinal resistance vanishes, if an external current is imposed. We found that the strong current imposed induces an asymmetry on the widths of the incompressible strips (ISs) depending linearly on the current intensity and can be balanced by an inhomogeneous donor distribution.

Investigation of the coupling asymmetries at double-slit interference experiments

Double-slit experiments inferring the phase and the amplitude of the transmission coefficient performed at quantum dots (QDs), in the Coulomb blockade regime, present anomalies at the phase changes depending on the number of electrons confined. This phase change cannot be explained if one neglects the electron–electron interactions. Here, we present our numerical results, which simulate the real sample geometry by solving the Poisson equation in 3D. The screened potential profile is used to obtain energy eigenstates and eigenvalues of the QD. We find that, certain energy levels are coupled to the leads stronger compared to others. Our results give strong support to the phenomenological models in the literature describing the charging of a QD and the abrupt phase changes.

Where are the edge-states near the quantum point contacts? A self-consistent approach

Abstract In this work, we calculate the current distribution, in the close vicinity of the quantum point contacts (QPCs), taking into account the Coulomb interaction. In the first step, we calculate the bare confinement potential of a generic QPC and, in the presence of a perpendicular magnetic field, obtain the positions of the incompressible edge states (IES) taking into account electron–electron interaction within the Thomas–Fermi theory of screening. Using a local version of Ohms law, together with a relevant conductivity model, we also calculate the current distribution. We observe that, the imposed external current is confined locally into the incompressible strips. Our calculations demonstrate that, the inclusion of the electron–electron interaction, strongly changes the general picture of the transport through the QPCs.