Theory of the spin-flip excitations in the ν=1 quantum Hall liquid

We calculated the spin-gap enhancement in the {ν}=1 quantum Hall liquid using a variational quantum Monte Carlo approach. The approach goes beyond the usual lowest-Landau-level approximation. A significant ({~}50% at rₛ=2) reduction in the single spin-flip gap due to Landau-level mixing is found for typical experimental situations. Final-state effects and the finite thickness of the electron gas are conveniently included in our formalism, and satisfactorily explain recent photoluminescence experiments on {δ}-doped samples.