Charged walls in amorphous magnetic films

Amorphous ferrimagnetic films of Gd
x
Co
1-x
, Gd
x
(Co
y
Ni
1-y
)
1-x
, and (Gd
x
Fe
1-x
)
0.9
B
0.1
were investigated by Ferrofluid techniques to establish the existence and properties of saw-tooth, or "charged)' walls. It was found that the walls existed with recognizable saw-tooth form if the product of magnetization (M
s
in Gauss) and film thickness (t in μm) was between 20 and 600 and the saw-tooth vertex angle followed the relation
\theta = \frac{\pi(\piA)^{1/2}}{2M_{s}t}+ C
where A is the exchange constant and C is an empirical correction to account for the angle below which charged walls can no longer exist due to high magnetostatic energy. Studies were made of wall motion and bubble rotation using amorphous drive layers.