Existence of a phase transition in a spin-1/2 Falicov-Kimball model

In this paper we present a proof for the existence of a phase transition in the symmetric case of the spin-1/2 Falicov-Kimball model in more than one dimension. For a certain regime of the parameters of this model we are able to show, that the superstructure of the localizedf-electrons in the ground-state, which has been investigated and published some time ago, persists in part up to small nonzero temperatures.Supported in part by the Deutsche Forschungsgemeinschaft