Impurity effects in few-electron quantum dots: Incipient Wigner molecule regime
Institut für Theoretische Physik,
Heinrich-Heine-Universität D-40225 Düsseldorf, Germany
Accepted: 18 July 2003
Numerically exact path-integral Monte Carlo data are presented for strongly interacting electrons confined in a 2D parabolic quantum dot, including a defect to break rotational symmetry. Low densities are studied, where an incipient Wigner molecule forms. A single impurity is found to cause drastic effects: 1) The standard shell-filling sequence with magic numbers N=4, 6, 9, corresponding to peaks in the addition energy , is destroyed, with a new peak at N=8; 2) spin gaps decrease; 3) for N=8, sub-Hund's rule spin S=0 is induced; and 4) spatial ordering of the electrons becomes rather sensitive to spin. We also comment on the recently observed bunching phenomenon.
PACS: 71.10.-w – Theories and models of many-electron systems / 73.21.La – Electron states: Quantum dots / 73.63.Kv – Electronic transport: Quantum dots
© EDP Sciences, 2003