One-dimensional wave equation for two electrons in nanoring whose height and width are much smaller than the diameter is derived. The energies of the two-electron low-lying states arising from the twoelectron rotation around the axis and their dependencies on the nanoring diameter, height and width are analysed. The level-ordering and crossovers of the corresponding curves related to the strong electronelectron interaction are studied and discussed. In the limit case as the height and width of the ring tend to zero our results coincide with those obtained previously for a one-dimensional nanoring.1 Introduction The understanding of the energy spectrum of few-electron quantum dots (QDs) is a key step toward the design of high performances devices. It is the reason why the energy spectrum of two electrons in QDs with parabolic or rectangular potential have been analysed by using different methods [1]. Commonly, QDs fabricated by using the Stranski-Krastanov method can have disk, lens or cone shape with circular top view cross section and a large area-to-height aspect ratio [2]. Recently, the realization of QDs with topology of a ring whose outer radius is between 30 and 70 nm, interior radius is about 10 nm and the height is between 2 and 4 nm, has been demonstrated [3], using the self-assembled techniques. The energy levels of two-electron quantum ring (QR) have been calculated and some differences and analogies between QDs and QRs have been discussed [4,5]. To analyse the electronic properties of QRs with two electrons a one-dimensional exactly solvable model which describes their rotation around the axis in the presence of the magnetic field, recently has been proposed [6]. In spite of that this model corresponds to a ring with infinite barrier potential and infinite radius-to-width aspect ratio, we consider that this exact solution could be used as starting point to analyse the electronic spectrum of more realistic two-electron QR models. In this paper we derive an equation for two-electron angular motion in a QR with a large radius-to-width aspect ratio and finite barrier potential within the framework of the adiabatic approximation applied previously to disk in Ref. [7]. We find that the parameters of this equation for a finite barrier potential depend strongly on the QR radius-to-width aspect ratio coinciding with those from Ref. [6] only when this ratio tends to zero and simultaneously the barrier potential tends to infinity. We present the results of calculation for the energies of several low-lying levels as a function of the QR radius and height. The analysis of the effect of the magnetic field on the two-electron ring energies is not included in the present work.

No abstract

Adopting a simple one-band tight-binding Hamiltonian and using the diagrammatic techniques for nonequilibrium processes proposed by Keldysh, we investigate the resonant tunneling transport properties through GaAs/Al x Ga 1Ϫx As double-barrier heterostructures under the action of in-plane and parallel magnetic field. The in-plane magnetic field leads to a shift to higher bias and a diminishing of the intensity of the resonant tunneling peak in the characteristic curves of current versus voltage in good agreement with experimental results. Also, we have found that the diminishing of the hopping energy between nearest neighbors is caused by the same effects as the in-plane magnetic field on the current-voltage characteristics. On the other hand, we have found that the intensity of the resonant peaks increases when the magnetic field is applied parallel to the current direction, an expected result due to the increasing values of the magnitude of the hopping parameter with the magnetic field. Our results compare quite well with experimental reports.

PAMELA: An open-source software package for calculating nonlocal exact exchange effects on electron gases in core-shell nanowires AIP Advances 2, 032173 (2012) Tunable electronic transport characteristics through an AA-stacked bilayer graphene with magnetoelectric barriers J. Appl. Phys. 112, 053714 (2012) Pinned interface dipole-induced tunneling electroresistance in ferroelectric tunnel junctions: A theoretical investigation J. Appl. Phys. 112, 054104 (2012) Current-voltage characteristics and ON/OFF ratio in ferroelectric tunnel junctions J. Appl. Phys. 112, 054102 (2012) Observation of fluctuation-induced tunneling conduction in micrometer-sized tunnel junctions AIP Advances 2, 032155 (2012) Additional information on J. Appl. Phys.

No abstract