The above discussion pertains to the ground state structure. Of course, finite temperatures lead to excitations of the spin configuration. Here two extreme points of view can be contrasted: in the Stoner picture of magnetism (also called itinerant magnetism), the electronic states are delocalized, and their mean-field interaction leads to the symmetry breaking. In this view, with increasing temperature the local magnetization would thus decrease homogeneously, as single delocalized electrons are moved from the up- to the down-channel. On the other hand, in the local-moment case the electronic states are localized to specific atoms, giving atomic spins, which interact only over a short range and typically are analyzed with the Heisenberg model. Here, finite temperatures lead to a deviation of the atomic spins' orientations from the ideal configuration, thus for a ferromagnet also decreasing the macroscopic magnetization.
