Electronic properties and spin polarization in coupled quantum dots

Electronic structure and charging properties of an electrostatically defined double quantum dot system are investigated within the local spin density approximation under the density functional theory. Characteristics of electron charging of the double dot system is influenced by quantum-mechanical as well as electrostatic coupling between the individual dots. In the case of weak coupling, the double dot system is shown to exhibit double electron charging in agreement with the observations of Waugh et al. [Phys. Rev. Lett. 75, 705 (1995)]. Also, the coupled dot system shows spin polarization for higher number of electrons in the dot N due to Hund’s rule. For strong coupling, we show that coherent bonding and antibonding states are formed which produce a reordering of the single-particle energy levels and revert the double dot system into a spin unpolarized state for same N.