Microstructural origin of the magnetically degraded layer in Sendust metal-in-gap recording heads

Microstructural studies using transmission electron microscopy have been performed on Sendust films deposited on both polycrystalline and single-crystal ferrites. A strain-induced contrast in both the ferrite and Sendust and a large number of dislocations in the ferrite region near the interface were observed. However, no intermediate layer of Al₂O₃ or SiO₂ was formed by interdiffusion at the interface. It was found that both the in-plane crystallographic texture and the microstructure of the Sendust films depend on the orientation of the underlying single-crystal ferrite substrates, even though the out-of-plane crystallographic texture appears to be independent of ferrite crystal orientation. A model has been proposed to explain the microstructural origin of the magnetically degraded layer formed at the interface of the Sendust film and ferrite cores in the MIG heads