Soft magnetic thin films of alloys of FeCoNi or FeCoDy and laminates comprising alternate layers of face centered cubic and body centered cubic crystal structure

DETAILED DESCRIPTION The present invention is aimed to provide improved soft magnetic properties of the Fe-Co base alloys and especially a soft magnetic thin film having good magnetic properties.
This invention provides a soft magnetic thin film used as the core etc, of the magnetic head, wherein the composition of the alloy having a basic composition of FeCoNi or FeCoDy is specified for use as a single layer film for increasing the saturation magnetic flux density and lowering the coercive force.
According to the present invention, better soft magnetic properties are achieved by laminating the above defined soft magnetic thin film as the first soft magnetic thin film layer with a second soft magnetic thin film layer.
In this case, crystal structures of the first and the second soft magnetic thin films should appropriately be selected and combined.
When the first film has a face-centered cubic structure (i.
e.
FeCoNi) it should be laminated with the second film having a body-centered cubic structure.
Inversely, the first film having a body-centered cubic structure (i.
e.
FeCoDy) should be combined with the second film having a face-centered cubic structure.
The soft magnetic thin film according to the present invention has a sufficiently low coercive force at the end of sputtering so that it does not impair the soft magnetic properties in the course of the heat processing such as the melting of glass when it is used as a single layer film for a magnetic head or the like.
When the soft magnetic thin film is used as the first soft magnetic thin film layer and laminated with the second soft magnetic thin film layer, soft magnetic properties are further improved.
When the soft magnetic thin film having these soft magnetic properties is used for the magnetic head, magnetization of the magnetic head is prevented and optimum recording and reproduction with only low distorsion and a high S/N ratio may be realized.