A derivation of the ordering part of the free energy functional based on an expansion about the free energy of a random CPA tight-binding paramagnetic effective medium is presented. Considering the dominant term of this functional, which is of Heisenberg form, the static magnetic correlation function is calculated within a spherical model approximation. For some parameters a behaviour characteristics for systems with tendency to form helicoidal ordered structure belowTc is observed.

On the short range magnetic order of iron aboveT c

The space extension of a single magnetization fluctuation in the disordered paramagnetic medium defined within the coherent potential approximation is discussed. The thermodynamical potential functional for the subspace of nearly completely disordered configurations is derived.

S. Lipiński

Papers

On the magnetization fluctuations in the completely disordered paramagnetic medium