Nagaoka ferromagnetism in the two-dimensional infinite-U Hubbard model

We present different numerical calculations based on variational quantum Mo nte Carlo simulations supporting a ferromagnetic ground state for finite an d small hole densities in the two-dimensional infinite-U Hubbard model. Mor eover, by studying the energies of different total spin sectors, these calc ulations strongly suggest that the paramagnetic phase is unstable against a phase with a partial polarization for large hole densities delta similar t o 0.40 with evidence for a second-order transition to the paramagnetic larg e doping phase.