We investigate the influence of electron correlations on the temperatu
re-dependence of the electronic structure of ferromagnetic bcc iron by
use of a many-body evaluation of a generalized model of magnetism. Th
e single-particle part of the model-Hamiltonian is taken from an LDA b
and structure calculation. The many-body interactions are described by
only two parameters, an intraband Coulomb interaction U and an interb
and exchange J. With U = 1.8 eV and J = 0.2 eV the self-consistent mod
el solution yields a T = 0 moment of about 2.04 mu(B) and a Curie-temp
erature of 1044 K. Details of the magnetic behaviour of Fe can be trac
ed back to a striking temperature variation of the quasiparticle densi
ty of states. A novel explanation for the experimentally-observed non-
collapsing exchange splitting is demonstrated in terms of the temperat
ure-dependent spectral density for wave-vectors near the GAMMA-point.
Typical differences in the magnetic behaviour of Fe and Ni are worked
out.