Ferromagnetic region

Fig. 6.7 Temperature dependence of the magnetic properties of hematite. Tc = Curie temperature,Tm = Morin temperature, pm = paramagnetic region, wfm = weakly ferromagnetic region afm = antiferromagnetic region. The insets show simulated Mossbauer spectra of hematite in the paramagnetic, weakly ferromagnetic and antiferromagnetic states (Murad, 1988, with permission).

If N>L+1, there are several pairs. It can be shown that all the pairs form a common ferromagnetic region [22]. Omitting manipulations which are similar to... 

The term H3 gives zero contribution to the ferromagnetic region energy). 

To minimize this function, we can evaluate the size of the ferromagnetic region and the energy and spin of the lattice ground state. For large values of X when a /, such a minimization gives... 

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