Abstract
On the basis of a spin-polarised density functional description of the electrons, the authors develop a 'mean-field' theory of magnetic phase transitions in metals. The one-electron-like finite-temperature Schrodinger equation is solved, formally, for random orientations of local moments and the corresponding grand potential is used in a statistical mechanics of the spin configurations. This latter, in the mean-field approximation, requires the knowledge of the electronic grand potential averaged over various ensembles of such 'spin' configurations. These averages are carried out with the help of the Korringa-Kohn-Rostoker coherent-potential-approximation (KKR CPA) method for dealing with electrons in random potential fields. Then, the whole procedure is made self-consistent on the average. The theory determines the local moment mu , the Curie temperature TC, and the susceptibility chi (q,T) in addition to the electronic structure at finite temperatures without adjustable parameters. The authors illustrate the explicit calculations for iron. The local moment is found to be 1.9 mu B above TC, and the preliminary estimate of Tc is 1250K.