Nagaoka ferromagnetism in the two-dimensional infinite-U Hubbard model.
We present different numerical calculations based on variational quantum Monte Carlo simulations supporting a ferromagnetic ground state for finite and small hole densities in the two-dimensional infinite-U Hubbard model. Moreover, by studying the energies of different total spin sectors, these calculations strongly suggest that the paramagnetic phase is unstable against a phase with a partial polarization for large hole densities delta approximately 0.40 with evidence for a second-order transition to the paramagnetic large doping phase.
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Istituto Nazionale per la Fisica della Materia and International School for Advanced Studies, Via Beirut 4, 34013 Trieste, Italy.
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