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 μ B atT=0) decreases forT→T c very similar to the 4f-magnetization. A red shift of the lower ↑-band edge of about 0.25 eV appears upon cooling fromT=T c toT=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 belowT c into four branches, two for each spin direction. TheirT-dependence mainly concerns the spectral weights of the quasiparticle peaks and not so much the energetic positions. An exchange caused splitting remains even forT<T c .