TEMPERATURE-DEPENDENT ELECTRONIC-STRUCTURE OF GADOLINIUM

Abstract

We investigate the electronic structure of the ferromagnetic 4f-metal Gadolinium by use of a many-body evaluation of a generalized model of magnetism, the one-particle part of which is derived from an ASW-LSDA bandstructure calculation. A striking temperature-dependence of the conduction band states is traced back to a 4f-(5d, 6s) interband exchange. The conduction electron polarization (0.63 mu(B) at T=0) decreases for T --> T(c) very similar to the 4f-magnetization. A red shift of the lower up-T-band edge of about 0.25 eV appears upon cooling from T=T(c) to T=0. - The quasiparticle band-structure exibits a remarkable non uniform magnetic behaviour at different positions in the Brillouin zone, and in particular for different subbands. Weakly correlated (''s-like'') dispersions show a `'Stoner-like'' T-dependence of the exchange splitting. On the other hand, stronger correlated (''d-like'') dispersions split below T(c) into four branches, two for each spin direction. Their T-dependence mainly concerns the spectral weights of the quasiparticle peaks and not so much the energetic positions. An exchange caused splitting remains even for T> T(c).