Exchange effects in an artificial atom at high magnetic fields

Abstract

A droplet of N∼30 electrons is created by lateral confinement of a two-dimensional electron gas. The evolution of its chemical potential μN with magnetic field B is inferred from resonant tunneling experiments and is used to study the dependence of its magnetization on B.The experimental data, quantitatively described by Hartree-Fock theory, suggest a divergent spin susceptibility at Bc implying a ground state of minimum total spin just below Bc. In the spin polarized regime we observe a new phase also predicted by Hartree-Fock theory. © 1995 The American Physical Society.