Coercivity of (YSmCa)3(FeGe)5O12LPE films

Optimum conditions for growing low coercivity Y
1.9
Sm
0.1
Ca
x
Ge
x
Fe
5-x
O
12
LPE films for 5μ bubble device application were determined from measurements of the influence of the underccoling /
0 < \DeltaT \leq 30\deg
C/, rotation rate /
0 \leq r \leq 300
rpm/ and melt composition /0.6
\leq \leq
Ca/Ge ≤ 1.4/ on coercivity. The coercive force /H
c
/ was measured by the oscillating stripe domain technique. The coercivity increases with supercooling and increasing GeO
2
content of the melt. Increased rotation rate reduces the coercivity to a nearly constant value above 100 rpm. From the wall displacement vs. drive field curves two distinct coercive forces can be defined. One of them, H
cl
is nearly independent of film thickness being the intrinsic "bulk" coercivity of the LPE layer. The higher one, H
c2
, increases hyperbolically with decreasing thickness and it is related to the transient layer formed at the beginning of the film growth.