Soft magnetic film having high saturation magnetic flux density, thin film magnetic head using the same, and methods of producing the soft magnetic film and the thin film magnetic head

A soft magnetic film having a composition represented by the formula Ni1-XFeX wherein the average crystal grain diameter is 130 Å to 175 Å, and the Fe composition ratio X is in the range of 70% by mass to 90% by mass.

A method of producing a soft magnetic film comprising plating a NiFe alloy by an electroplating method using a pulsed current, wherein the Ni ion concentration of a plating bath is 6.6 g/l to 20 g/l, and the ratio of the Fe ion concentration to the Ni ion concentration is 0.15 to 0.36.

A thin film magnetic head comprising a lower core layer made of a magnetic material, an upper core layer formed on the lower core layer with a magnetic gap provided therebetween, and a coil layer for supplying a recording magnetic field to both core layers;

• wherein at least one of the core layers comprises a soft magnetic film represented by the composition formula Ni1-XFeX, and having a Fe composition ratio X of 76% by mass to 90% by mass.

A thin film magnetic head comprising a lower core layer, an upper core layer, and a pole portion located between the lower core layer and the upper core layer and having a width dimension in the track width direction, which is defined to be shorter than the lower core layer and the upper core layer;

• wherein the pole portion comprises a lower pole layer continued from the lower core layer, an upper pole layer continued from the upper core layer, and a gap layer positioned between the lower pole layer and the upper pole layer, or an upper pole layer continued from the upper core layer and a gap layer positioned between the upper pole layer and the lower core layer;
• and
• wherein the upper pole layer and/or the lower pole layer comprises a soft magnetic film represented by the composition formula Ni1-XFeX, and having a Fe composition ratio X of 76% by mass to 90% by mass.

A method of manufacturing a thin film magnetic head comprising a lower core layer made of a magnetic material, an upper core layer opposed to the lower core layer with a magnetic gap provided therebetween at a surface facing a recording medium, and a coil layer for inducing a recording magnetic field in both core layers, the method comprising:

• forming the upper core layer and/or the lower core layer by plating a NiFe alloy by an electroplating method using a pulsed current, wherein the Ni ion concentration of a plating bath is 6.6 g/l to 20 g/l, and the ratio of the Fe ion concentration to the Ni ion concentration is 0.15 to 0.36.