Symmetry and spin polarization in single and coupled quantum dots

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Abstract
We conducted theoretical investigation into the effect of spontaneous electron spin polarization in single and coupled quantum dots formed by lateral confinement of a high-mobility two-dimensional electron gas in a semiconductor heterostructure. The equilibrium properties of realistic many-electron quantum-dot devices are first studied within the two-dimensional Thomas-Fermi approximation taking into account contributions from the patterned gate, doping, surface states, and mirror charges. In order to explore spin-dependent phenomena, a self-consistent model has been developed using the Kohn-Sham local spin-density formalism. We have tested the contribution of electron correlation in the systems considered and found that it plays a minor role, hence only exchange interactions are included in the model. We investigate the possibilities of manipulating the magnetization (spin polarization) of single and double quantum dots by means of their mutual coupling and symmetry breaking caused by variations in the geometry of the gate.