Soft magnetic properties and microstructure of NiFe(Cr)/FeCo/NiFe(Cr) films with large saturation magnetization

The soft magnetic properties of FeCo films, sandwiched by thin NiFe or NiFeCr films, are discussed in relation to the microstructure. Ta/NiFe(Cr)(5 nm)/FeCo(100 nm)/NiFe(Cr)(5 nm)/Ta films prepared using the URV sputtering process with pure Ar plasma show bcc(110) preferred grain orientation of FeCo layer with the <110> direction sharply perpendicular to the film plane, resulting in soft magnetic properties. No significant difference in soft magnetic properties was observed by the use of nonmagnetic NiFeCr layers instead the NiFe layers, moreover, by varying FeCo composition between 25 and 30 at%Co. The best thickness of the FeCo layer in order to realize soft magnetic properties was found to be similar to100 nm in the present study, with a high saturation magnetization of 2.3 T. An addition of N-2 gas to Ar plasma during film deposition did not lead to an improvement of the soft magnetic properties. A film of [FeCo(100 nm)/NiFe(5 nm)]4 layer structure was subjected to the fabrication of single-pole-type recording head, and it is successfully demonstrated that the film has a sufficient softness to be used for the recording head application.