Analysis of metal-ferrite interface layers in metal-in-gap heads

A metal-in-gap head structure in which the metal/ferrite interface is perfectly parallel to the main gap face was adopted for mass-production. An analysis of a pseudo-gap formed at the metal-ferrite interface by using sputter-assisted Auger electron spectroscopy is reported. In the case of a Sendust MIG head, it is confirmed that the pseudo-gap is a reacted layer at the metal-ferrite interface, which consists of Al₂O₃+SiO₂. The reaction mechanism is examined in the case of Sendust/MnZn-ferrite and a soft magnetic alloy, called Sofmax, and suitable barrier materials and thickness ranges. It is found that the reacted layer is reduced drastically by using a SiO₂ or SiN₂O 5-10 nm thick ultrathin barrier layer and Sofmax alloy film instead of Sendust. The ripple of a parallel-type metal-in-gap heads is found to be 0.5 dB or less