Abstract: A magnetic disk apparatus includes a magnetic disk for recording information and a magnetic head which has a reproducing head and a recording head. The reproducing head comprising a lower shield film, a magnetoresistive film, a pair of electrodes and an upper shield, and the recording head comprising an upper magnetic core, a lower magnetic core, and a coil disposed between said upper magnetic core and said lower magnetic core. The upper magnetic core and the lower magnetic core include an electroplated thin film with an average crystal grain size smaller than 500 Å, and the electroplated thin film is made of Ni—Fe alloy of which Ni is 38 to 60 wt % and Fe is 40 to 62 wt %.

Abstract: A slider having a thin film magnetic head. The thin film magnetic head has an upper magnetic core, a lower magnetic core and a coil disposed between the upper magnetic core and the lower magnetic core. The upper magnetic core and the lower magnetic core is an electroplated thin film with an average crystal grain size smaller than 500A.

Abstract: A slider having a thin film magnetic head. The thin film magnetic head has an upper magnetic core, a lower magnetic core and a coil disposed between the upper magnetic core and the lower magnetic core. The upper magnetic core and the lower magnetic core is an electroplated thin film with an average crystal grain size smaller than 500 Å, and the electroplated thin film is made of Ni—Fe alloy of which Ni is 38 to 60 wt % and Fe is 40 to 62 wt %.

Abstract: A slider having a thin film magnetic head. The thin film magnetic head has an upper magnetic core, a lower magnetic core and a coil disposed between the upper magnetic core and the lower magnetic core. The upper magnetic core and the lower magnetic core is an electroplated thin film with an average crystal grain size smaller than 500 Å, and the electroplated thin film is made of Ni—Fe alloy of which Ni is 38 to 60 wt% and Fe is 40 to 62 wt%.

Abstract: A thin film magnetic head having a first magnetic core, a second magnetic core formed on the first magnetic core, a coil disposed between the first magnetic core and second magnetic core, and a non-magnetic insulator body for separating the first magnetic core, second magnetic core and coil with respect to each other. At least one of the first magnetic core and the second magnetic core includes an electroplated thin film with an average crystal grain size smaller than 500 Å and the electroplated thin film is made of Ni—Fe alloy of which Ni is 38 to 60 wt % and Fe is 40 to 62 wt %.

Abstract: A thin magnetic head having a first magnetic core, a second magnetic core formed on the first magnetic core, a coil disposed between the first magnetic core and second magnetic core, and a non-magnetic insulator body for separating the first magnetic core, second magnetic core and coil with respect to each other. At least one of the first magnetic core and the second magnetic core includes an electroplated thin film with a crystal grain size smaller than 500 Å and the electroplated thin film is made of Ni—Fe alloy of which Ni is 38 to 60 wt % and Fe is 40 to 62 wt %.

Abstract: A thin film magnetic head and a disk storage system having a magnetic disk and the thin film magnetic head provided on a floating type slider. The thin film magnetic head has an upper magnetic core and a lower magnetic core, wherein the upper magnetic core and the lower magnetic core are made of an electroplated thin film having sufficient average crystal grain size. The upper magnetic core is made of a Ni—Fe alloy having Ni of 38 to 60 wt % and Fe of 40 to 62 wt %, and the crystal grain size is smaller than 500 Å.

Abstract: A magnetic film having a high saturation magnetic flux density larger than 1.5 T and a resistivity larger than 40 .mu..OMEGA..cndot.cm is fabricated through an electroplating method using (40-60)Ni-Fe and by adding Co, Mo, Cr, B, In, Pd or the like to the (40-60)Ni-Fe. Thereby, it is possible to obtain a recording head capable of performing sufficient recording in a high frequency range and to obtain a disk storage system with a high recording density which has a transfer rate higher than 15 MB/s, a recording frequency higher than 45 MHz and a rotating speed of a magnetic disk higher than 4000 rpm.