Magnetic shield, manufacturing method thereof and thin film magnetic head employing the same

2+ 2+Embodiments of the present invention provide a magnetic shield composed of size-controlled small crystal grains and provide a more after-write read noise free thin film magnetic head. According to one embodiment of the present invention, an upper magnetic shield uses a multi-layered magnetic film formed by alternately stacking a face-centered cubic (fcc) crystalline magnetic thin layer and a body-centered cubic (bcc) crystalline magnetic thin layer by plating. The plating bath is such that the temperature is 30±1° C., pH is about 2.0−1.0 to 2.0+0.5, metal ion concentrations are about 5 to 25 (g/l) for Niand 5 to 15 (g/l) for Fe, saccharin sodium concentration is about 1.5±1.0 (g/l), sodium chloride concentration is about 25±5 (g/l), and boric acid concentration is about 25±5 (g/l). Each layer's crystal structure is different from that of its upper and lower layers, which results in size-controlled small crystal grains since the epitaxial growth is broken. Since crystal grains are reduced in size, it is possible to suppress the after-write read noise and therefore attain a read head which allows recording at higher frequencies.