Spin polarization of electrons in GaAs quantum dots: role of electron correlations

The ground state behaviour of GaAs quantum dots with N = 2-6 electrons in a magnetic field of B = 0-5 T is investigated in the Hartree-Fock (HF) approximation, and then the correlation effects are taken into account via a local-density-functional approach. It is found that in the HF approximation the dot electrons have already been in spin-polarized states at small B, even at B = 0 T for most cases. However when the electron correlations are included all the spin-polarized states at small B are suppressed and the ground states of all cases around B = 0 are normal states with S = 0 or 1/2 for even or odd number of electrons. As B is increased to 1.83-2.64 T the ground states will directly transit from normal states to their corresponding fully spin-polarized states.