Re-entrant pinning of Wigner molecules in a magnetic field due to a Coulomb impurityB. Szafran1, 2 and F. M. Peeters1
1 Departement Natuurkunde, Universiteit Antwerpen (Campus Drie Eiken) B-2610 Antwerpen, Belgium
2 Faculty of Physics and Nuclear Techniques, AGH University of Science and Technology - al. Mickiewicza 30, 30-059 Kraków, Poland
(Received 5 December 2003; accepted in final form 29 March 2004)
Pinning of magnetic-field-induced Wigner molecules (WMs) confined in parabolic two-dimensional quantum dots by a charged defect is studied by an exact diagonalization approach. We found a re-entrant pinning of the WMs as a function of the magnetic field, a magnetic-field-induced re-orientation of the WMs and a qualitatively different pinning behaviour in the presence of a positive and negative Coulomb impurity.
73.21.La - Quantum dots.
73.20.Qt - Electron solids.
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