Intermediate Low Spin States in a Few-electron Quantum Dot in the $\nu \le 1$ Regime

We study the effects of electron-electron interactions in a circular few-electron vertical quantum dot in such a strong magnetic field that the filling factor $\nu \le 1$. We measure excitation spectra and find ground state transitions beyond the maximum density droplet ($\nu =1$) region. We compare the observed spectra with those calculated by exact diagonalization to identify the ground state quantum numbers, and find that intermediate low-spin states occur between adjacent spin-polarized magic number states.