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

Optimum conditions for growing low coercivity Y1.9Sm0.1CaxGexFe5-xO12LPE films for 5μ bubble device application were determined from measurements of the influence of the underccoling / C/, rotation rate / rpm/ and melt composition /0.6 Ca/Ge ≤ 1.4/ on coercivity. The coercive force /Hc/ was measured by the oscillating stripe domain technique. The coercivity increases with supercooling and increasing GeO2content 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, Hclis nearly independent of film thickness being the intrinsic "bulk" coercivity of the LPE layer. The higher one, Hc2, increases hyperbolically with decreasing thickness and it is related to the transient layer formed at the beginning of the film growth.