THIN FILM MAGNETIC HEAD AND METHOD OF MANUFACTURING THE SAME
A thin film magnetic head is disclosed having a non-magnetic layer that is formed of a NiPRe (nickel-phosphorus-rhenium) alloy, which makes it possible to optimize the composition ratios of elements Ni, P, and Re, to obtain the non-magnetic layer having a smooth surface, and to prevent concave portions from being formed in both side surfaces of the non-magnetic layer during a milling process, thereby improving recording characteristics. The composition ratio of a NiPRe alloy forming the non-magnetic layer is set within the range surrounded by boundary lines A to D in a ternary diagram, which makes it possible to form a non-magnetic layer having a smooth surface and uniformly form the magnetic layer on the non-magnetic layer. In addition, since the NiPRe alloy having the composition ratio has a low milling rate, it is possible to prevent concave portions from being formed in both side surfaces of the magnetic layer that is formed on or underneath the non-magnetic layer. As a result, it is possible to accurately regulate a recording track width to a narrow width and thus improve recording characteristics.
1 . A thin film magnetic head comprising:
a magnetic layer; and
a non-magnetic layer that is provided on or underneath the magnetic layer, wherein the non-magnetic layer is formed of a NiPRe alloy by plating, and in a ternary diagram shown in FIG. 3 , the composition ratio of the NiPRe alloy is within the range surrounded by:
a straight boundary line A (not including points on the boundary line A) linking a point a (Ni:P:Re)=(84 mass %: 16 mass %: 0 mass %) and a point b (Ni:P:Re)=(72 mass %: 0 mass %: 28 mass %);
a straight boundary line B (including points on the boundary line B) linking points where the composition ratio of Re is 2 mass %;
a straight boundary line C (including points on the boundary line C) linking points where the composition ratio of Re is 12 mass %; and
a straight boundary line D (including points on the boundary line D) linking points where the composition ratio of P is 8 mass %.
2 . The thin film magnetic head according to claim 1 ,
wherein the non-magnetic layer is a gap layer interposed between an upper magnetic layer and a lower magnetic layer, and
at least the lower magnetic layer and the gap layer form a track width regulating portion that regulates a track width Tw in a surface opposite to a recording medium.
3 . The thin film magnetic head according to claim 1 ,
wherein the thin film magnetic head is a vertical magnetic recording type including a main magnetic pole layer, and
the magnetic layer is the main magnetic pole layer.
4 . A method of manufacturing a thin film magnetic head including a magnetic layer and a non-magnetic layer that is provided on or underneath the magnetic layer, comprising:
forming the magnetic layer by plating;
plating the magnetic layer with a NiPRe alloy to form the non-magnetic layer on or underneath the magnetic layer; and
milling both side surfaces of the magnetic layer in a track width direction to regulate a track width Tw,
wherein, in a ternary diagram shown in FIG. 3 , the composition ratio of the NiPRe alloy is within the range surrounded by:
a straight boundary line A (not including points on the boundary line A) linking a point a (Ni:P:Re)=(84 mass %: 16 mass %: 0 mass %) and a point b (Ni:P:Re)=(72 mass %: 0 mass %: 28 mass %);
a straight boundary line B (including points on the boundary line B) linking points where the composition ratio of Re is 2 mass %;
a straight boundary line C (including points on the boundary line C) linking points where the composition ratio of Re is 12 mass %; and
a straight boundary line D (including points on the boundary line D) linking points where the composition ratio of P is 8 mass %.
5 . The method of manufacturing a thin film magnetic head according to claim 4 ,
wherein at least a lower magnetic layer and a gap layer, which is the non-magnetic layer, form a track width regulating portion,
in the forming of the non-magnetic layer, the lower magnetic layer is formed by plating and then the gap layer is formed by plating, and
in the milling of both side surfaces of the magnetic layer, milling is performed on both side surfaces of each of the gap layer and the lower magnetic layer.