Ground state and vortex structure of theN=5andN=6electron quantum dot

A system of $N=5$ and 6 two-dimensional Coulomb-interacting electrons, trapped in a harmonic potential and subjected to a perpendicular magnetic field, is studied using an exact-diagonalization technique. The results are summarized in a phase diagram, indicating the ground state as a function of the magnetic field and the electron-electron interaction strength. The transformation to a Wigner crystal after the breakdown of the maximum density droplet is investigated and is related to the vortex structure of the different states. The internal structure of the composite fermion is investigated as function of the magnetic field and related to several properties of the quantum dot (e.g., compressibility, liquid or crystal, stability of the ground state, and so on).