On the Theory of Free Electron Ferromagnetism

A calculation has been made of the ferromagnetic properties of a system of electrons using plane wave functions and Bloch exchange integrals. Our results show that below a critical temperature T c the spontaneous magnetization decreases slowly with increasing temperature. At T c the magnetization drops suddenly to zero as if a change of phase were taking place and there is therefore a latent heat of demagnetization at this temperature. Above T c the model is paramagnetic. The reasons for the differences between the results and those obtained by experiment and on Stoner's theory of collective electron ferromagnetism are discussed, and the possibility that they may be due to the neglect of positional correlations among the electrons is considered.