Electronic structure of metallic ferromagnets above the Curie temperature

Cf. Gyorffy et al., ibid. , p 1337. The electronic structure of Fe and Ni is described above their Curie temp. in their disordered local moment (DLM) states as a function of wavevector k and energy epsilon . In particular, the Bloch spectral function, A(k, epsilon ), averaged over the orientational configurations of the local moments, is calculated at selected points in the Brillouin zone and the shape and smearing of the `Fermi surface' is determined. BCC Fe, with a local moment of 1.9 mu sub B , can show an exchange splitting at some points whilst in other regions of the Brillouin zone no such splitting occurs. For comparison FCC Fe, which also supports a substantial local moment was studied and was found to have similar features, but the smearing of the `bands' is more pronounced. On the other hand, the electronic structure of Ni is quite different, shows no such local exchange splitting, but is able to support a small local moment of 0.2 mu sub B . The resulting picture for the electronic structure of Ni is that of a paramagnetic smeared "Stoner--Wohlfarth" model. 30 ref.--AA