Gunnar Thorgilsson

Rashba spin-orbit interaction in a superlattice of quantum wires

Gunnar Thorgilsson, J. Carlos Egues, 3 Daniel Loss, and Sigurdur I. Erlingsson Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik, Iceland Departamento de F́ısica e Informática, Instituto de F́ısica de São Carlos, Universidade de São Paulo, 13560-970 São Carlos, SP, Brazil Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland Reykjavik University, School of Science and Engineering, Menntavegi 1, IS-101 Reykjavik, Iceland

Transient magnetotransport through a quantum wire

We consider an ideal parabolic quantum wire in a perpendicular magnetic field. A simple Gaussian-shaped scattering potential well or hill is flashed softly on and off with its maximum at

Time-dependent magnetotransport of a wave packet in a quantum wire with embedded quantum dots

t=0

Electronic states in core-shell quantum rings

, mimicking a temporary broadening or narrowing of the wire. By an extension of the Lippmann-Schwinger formalism to time-dependent scattering potentials, we investigate the effects on the continuous current that is driven through the quantum wire with a vanishingly small forward bias. The Lippmann-Schwinger approach to the scattering process enables us to investigate the interplay between geometrical effects and effects caused by the magnetic field.

Transport in four-terminal semiconductor nanostructures with Rashba spin–orbit interaction

We consider wave packet propagation in a quantum wire with either an embedded antidot or an embedded parallel double open quantum dot under the influence of a uniform magnetic field. The magnetoconductance and the time evolution of an electron wave packet are calculated based on the Lippmann-Schwinger formalism. This approach allows us to look at arbitrary embedded potential profiles and illustrate the results by performing computational simulations for the conductance and the time evolution of the electron wave packet through the quantum wire. In the double-dot system, we observe a long-lived resonance state that enhances the spatial spreading of the wave packet, and quantum skippinglike trajectories are induced when the envelop function of the wave packet covers several subbands in appropriate magnetic fields.

Effects of scattering area shape on spin conductance in a four-terminal spin-Hall setup

We compare energy levels, carrier localization and optical absorption of a single electron and a pair of interacting carriers confined in a hexagonal quantum ring. We show that many-body levels are multiple degenerate and, contrary to the single-particle case, no repeated energy sequence can be identified. The number of eigenvalues associated with corner-localized probability distributions increases with the number of particles. In both the cases that we analyzed, the largest values of absorption coefficients correspond to transitions in the corner-localized domain.

Multi-domain electromagnetic absorption of triangular quantum rings.

We studied spin transport in a four-terminal system with Rashba spin?orbit coupling. Using discretization, we convert the non-equilibrium Greens function equations into matrix equations, which are then solved using the recursive Greens function method. The calculations show that having round edges in the scattering region leads to a more regular spin polarization, indicating that the shape of the scattering region can be used as an additional control for spintronics applications.

Thermoelectric current in tubular nanowires in transverse electric and magnetic fields

We study spin conductance in a ballistic and quasi-ballistic two dimensional electron system with Rasbha spin-orbit coupling. The system has a four-terminal geometry with round corners at the connection to the leads. It is found that by going from sharp corners to more round corners in the ballistic system the energy depended spin conductance goes from being relatively flat to a curve showing a series of minima and maxima. It is also found that when changing the size of the terminal area by modifying the roundness of the terminal corners the maxima and minima in the transverse spin conductance are shifted in energy. This shift is due increased (decreased) energy for smaller (larger) terminal area. These results were also found to be reasonably stable in quasi-ballistic systems.