ELECTRONIC QUASI-PARTICLE STRUCTURE OF FERROMAGNETIC BCC IRON

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