Many-body effect in an artificial atom

Atomic-like properties of vertical quantum dots are studied by measuring Coulomb oscillations. The Coulomb oscillations in the linear transport regime become irregular in period, reflecting a shell structure and the obedience to Hund's rule, as the number of electrons in the dot approaches zero. Under a high magnetic field, many-body effects become important, and we observe kink structures in the few-electron regime in the Coulomb oscillation peak positions versus the magnetic field. The kink structures are well assigned to transition in spin and angular momentum states, which we predict by the exact diagonalization approach. (orig.)