Conductance of an Artificial Atom in Strong Magnetic Fields

The conductance resulting from resonant tunneling through a droplet of $N \sim 30$ electrons is used to measure its chemical potential $\mu_N$. Abrupt shifts of $\mu_N$ occur at sharply defined values of the magnetic field, at which the state of the droplet changes. These are used to study part of the phase-diagram of the droplet in strong magnetic fields; we find evidence for a new phase in the spin polarized regime. We make a detailed comparison between theory and experiment: Hartree-Fock provides a quantitative description of the measurements when both spin-split states of the lowest orbital Landau level are occupied and a qualitative one in the spin polarized regime.