Quantum dots with interacting electrons: Energy spectra and magnetization

Abstract

The energy spectra and magnetization of a two-electron, square quantum dot is investigated theoretically by numerical diagonalization of the many-particle Hamiltonian of the system. The electron–electron interaction is found to lift many degeneracies between spin–singlet and spin–triplet states of noninteracting electrons and induce many energy level crossings and anticrossings. It is found that the interaction increases the magnitude of magnetization in the low magnetic field region and induce magnetization oscillations in the moderate and strong field regions. The effect of the interaction on the magnetization is also studied when a repulsive δ–function impurity is present at the center of the quantum dot. The impurity is found to weaken the many–particle effect on the magnetization in the low magnetic field region. It is also found that the interaction tends to screen the impurity and weaken the effect of the impurity in the quantum dot.