Nagaoka ferromagnetism in doped Hubbard models in optical lattices

Finding ferromagnetic ground states of the Hubbard model, which usually features antiferromagnetic spin correlations, has been an outstanding challenge since Nagaoka's celebrated (but experimentally unrealistic) proposal in 1966. Here, the authors show how such elusive itinerant ferromagnetism can be enhanced by kinetic frustration or occupation-dependent hoppings and demonstrate the relevance of these mechanisms to recent optical-lattice experiments.