Magnetic phase diagram of the hubbard model with next-nearest-neighbour hopping

Abstract

We calculate the magnetic phase diagram of the Hubbard model for a Bethe lattice with nearest-neighbour (NN) hopping t1 and next-nearestneighbour (NNN) hopping t2 in the limit of infinite coordination. We use the amplitude t2/t1 of the NNN hopping to tune the density of states (DOS) of the non-interacting system from a situation with particle-hole symmetry to an asymmetric one with van-Hove singularities at the lower (t2/t1>0) respectively upper (t2/t1<0) band edge for large enough |t 2/t1|. For this strongly asymmetric situation, we find rather extended parameter regions with ferromagnetic states and regions with antiferromagnetic states. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.