Interacting electrons in artificial molecules with magnetic field of arbitrary direction

We theoretically investigate the mechanisms for the magnetic field-induced singlet-triplet transition of two electrons in vertically coupled quantum dots, as a function of the field strength and direction. Our numerical approach is based on a real-space description of single-particle states in realistic samples and exact diagonalization of carrier-carrier Coulomb interaction. The three-electron system is also discussed, and we show that the magnetic field drives non-trivial transitions in the ground and excited states. (C) 2004 Elsevier B.V. All rights reserved.