Skyrmions without sigma models in quantum Hall ferromagnets

We report on a microscopic theory of the Skyrmion states that occur in the quantum Hall regime. The theory is based on the identification of Skyrmion states in this system with zero-energy eigenstates of a hard-core model Hamiltonian. We find that for N-phi orbital states ina Landau level, a set of Skyrmion states with orbital degeneracy N-phi - K and spin quantum number S = N/2 - K exists for each non-negative integer K. The energetic ordering of states with different K depends on the interaction potential.