Spin-orbit effects on two-electron states in nanowhisker double quantum dots

Abstract

We investigate theoretically the combined effects of the electron-electron and the Rashba spin-orbit interactions on two electrons confined in quasi-one-dimensional semiconductor double quantum dots. We study both InSb-based structures, which are of interest due to their strong spin-orbit coupling, and also InAs-based systems, which have been recently studied experimentally. We calculate the two-electron wave functions in the effective-mass approximation and explore the interplay between the two interactions on the energy levels and the spin of the states. The energy spectrum as a function of an applied magnetic field shows crossings and anticrossings between triplet and singlet states, associated with level mixing induced by the spin-orbit coupling. We find that the fields at which these crossings occur can be naturally controlled by the interdot barrier width, which controls the exchange integral in the structure. © 2009 Elsevier B.V. All rights reserved.