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Exchange field


\begin{displaymath} \mathbf{H}_\mathrm{exch}=\sum^{NN}_j \frac{2 A}{\Delta x^2} \mathbf{M}_j \end{displaymath}

$NN$   sum is taken over all nearest neighbours,
$j$   index of the nearest neighbour,
$A$ (J/m) exchange constant,
$\Delta x$ (m) nearest neighbour distance,
$\mathbf{M}_j$ (A/m) magnetization vector of the nearest neighbour $j$


Werner Scholz 2000-05-16