Magnetic properties of Co-Cr/mumetal double layer films

A dc magnetron sputtered multilayer (Co-Cr mumetal) film is examined for magnetic coupling of the sublayers. No evidence for physical coupling is observed. The multilayer coercivity near the perpendicular direction has a strong dependence on angle due to the planar mumetal component. The coercivity of the mumetal exhibits Kondorsky-type angular behavior. Coercivities of the Co-Cr film measured parallel and perpendicular to the field direction both decrease linearly from 100 K to 340 K, with a room temperature coefficient
\beta = (1/H_{c})(\DeltaH_{c}/\DeltaT) = -0.2
percent/K. The temperature dependence of coercivity can be modeled on a domain wall pinning theory, based on exchange fluctuations over a small domain wall area. It is shown that high Curie temperatures are needed to minimize thermal variation in recording output signal. X-ray transmission attenuation is shown to be a useful tool for determining the Co-Cr thickness in a multilayer film.