Static wall coercive force in ferromagnetic thin films

The static wall coercive force of thin ferromagnetic films has been calculated from a model of conservative wall energy. The spatial dependence of the wall energy γ
w
is assumed to be given by the mean value of the local anisotropy energy, averaged over a coupling volume of the wall. The result of the calculation shows that
H_{w} \propto \frac{S}{M_{s}} (\frac{D}{W})^{1/2} \frac{1}{L}
where the structure constant
S
includes the local anisotropy,
D
is the mean diameter of a region with constant anisotropy (for instance crystallites),
W
is the wall width; and
L
is the coupling length parallel to the wall.