  Quantum antidot, a small potential hill introduced into a two-dimensional
electron system, presents an attractive tool to study quantum mechanics of
interacting electrons.Here, we report experiments on electron resonant
tunneling via a quantum antidot on the integer i = 1, 2, 3, 4, 5, and 6 quantum
Hall plateaus. Several new features are reported. First, as a function of
magnetic field, we observe up to six quasiperiodic resonant tunneling peaks
within the fundamental flux period: when flux h/e is added to the area of the
antidot there are i peaks on the i-th integer plateau, when i spin-polarized
Landau levels are occupied. Corresponding back gate voltage data show one peak
per added charge e on all integer plateaus. Second, we observe tunneling dips
in four-terminal resistance ("forward scattering") on the even i = 2, 4, and 6
plateaus, when population of both spins is nearly equal. Also, for the first
time, we report an internal structure within the h/e period: on the i = 3
spin-split plateau, two of the three resonant tunneling peaks are higher and/or
closer than the third. Puzzlingly, in this regime, when back gate voltage is
swept, the tunneling peaks are grouped in pairs. These results are attributed
to the dominance of the electron-electron Coulomb interaction, effectively
mixing Landau level occupation, and to the self-consistent electrostatics of
the antidot.
