Exact diagonalization studies of the level density in a six-electron quantum dot under magnetic fields around 7 T (``filling factor'' around 1/2) are reported. In any spin-polarization channel, two regimes are visible in the dot excitation spectrum: one corresponding to interacting quasiparticles (i.e. composite fermions) for excitation energies below 0.4 meV, and a second one for energies above 0.4 meV, in which the level density (exponentially) increases at the same rate as in the non-interacting composite-fermion model.
@article{arxiv.cond-mat/0207537,
title = {Discontinuities in the level density of small quantum dots under strong magnetic fields},
author = {Augusto Gonzalez and Roberto Capote},
journal= {arXiv preprint arXiv:cond-mat/0207537},
year = {2009}
}