Electron transfer through a multiterminal quantum ring: Magnetic forces and elastic scattering effects

Abstract

We study electron transport through a semiconductor quantum ring with one input and two output terminals for an elastic scatterer present within one of the arms of the ring. We demonstrate that the scatterer not only introduces asymmetry in the transport probability to the two output leads but also reduces the visibility of the Aharonov-Bohm conductance oscillations. This reduction occurs in spite of the phase coherence of the elastic scattering and is due to interruption of the electron circulation around the ring by the potential defect. The results are in a qualitative agreement with a recent experiment by Strambini et al. [Phys. Rev. B 79, 195443 (2009)]. We also indicate that the magnetic symmetry of the sum of conductance of both the output leads as obtained in the experiment can be understood as resulting from the invariance of backscattering to the input lead with respect to the magnetic field orientation.

Magnetic forces and stationary electron flow in a three-terminal semiconductor quantum ring

“…In finite temperature the dips and peaks of the transfer probabilities are transformed into smooth extrema of reduced amplitude which eventually disappear at high magnetic field. The attenuation of the Aharonov-Bohm oscillations of the transfer probabilities for non-zero temperatures at higher B is in agreement with the results of previous wave packet simulations [17][18][19] , in which the averaging of the transfer probabilities with k are embedded in the initial condition. The attenuation was also observed in the experimental data of Ref.…”

“…For k = 0.057 nm −1 the electron is directed to the left arm of the ring and then to the left output channel as previously described by the time dependent calculations. [17][18][19] For k = 0.0577 nm −1 the current forms vortices in the left arm and the actual electron transfer occurs through the right arm of the ring. For k = 0.0577 nm −1 the current goes through the right arm but the electron transfer to the right lead has still low probability.…”

“…The dominant electron trajectory for this transport conditions was indicated in Ref. [19] using wave packet simulations.…”

“…These conductance oscillations are extensively studied in the context of scanning gate spectroscopy, 10 spin-orbit coupling for both electrons 11,12 and holes, 13 Aharonov-Bohm interferometry 14 including electron self-interference, 15 violation of Onsager symmetry, 16 and magnetic forces. [17][18][19][20] The deflection of electron trajectories by magnetic forces in two-terminal quantum rings was previously studied by time-dependent wave packet simulations 17 which indicated that in presence of external perpendicular magnetic field the electron packet is preferentially injected into one of the arms of the ring which reduces the Aharonov-Bohm interference of electron waves meeting near the exit to the output lead. A time-dependent simulation was also used to describe the transport through a three-terminal quantum ring, 18 which demonstrated that the Lorentz force -besides the reduction of the Aharonov-Bohm oscillations at high field -results in a distinct imbalance of the wave packet transfer probabilities to the two output leads.…”

Two-dimensional quantum rings with oscillating spin-orbit interaction strength: A wave function picture

“…Magnetic field related effects in ring shaped objects with finite width have also been investigated intensively. [24][25][26][27][28][29] Our approach is similar to that of Ref. [30], where the features of certain low-lying states as a function of the (constant) Rashba SOI were investigated, and Refs.…”