The maximum-density-droplet (MDD) state of quantum-dot electrons becomes unstable in strong magnetic fields to the addition of interior holes. Using exact diagonalization, we demonstrate that the first hole is located at the center of the dot when the number of electrons N is smaller than $\sim 14$ and is located away from the center for larger dots. The separation between field strengths at which additional holes are introduced becomes small for large dots, explaining recent observations of a rapid increase in dot area when the magnetic field is increased beyond the MDD stability limit. We comment on correlations between interior hole and collective edge fluctuations, and on the implications of these correlations for edge excitation models in bulk systems.

• Received 4 March 2002

DOI:https://doi.org/10.1103/PhysRevB.66.041304