Thin film magnetic head and magnetic disk apparatus using the same

A thin film magnetic head comprising:

• a first magnetic yoke having a first magnetic pole facing a magnetic recording medium;
• a second magnetic yoke having a second magnetic pole so disposed as to define a magnetic gap between the first magnetic pole and the second magnetic pole and forming at a rear portion of the second magnetic yoke a magnetic circuit which magnetically short-circuits to said first magnetic yoke;
• a conductor coil formed between said first and second magnetic yokes;
• and
• an insulating layer for insulating said conductor coil from said first and second magnetic yokes,
• wherein said second magnetic yoke has a magnetic gap depth over which the spacing of the magnetic gap defined between said first and second magnetic yokes keeps substantially equal toward the rear portion of said second magnetic yoke, starting at the tip of said second magnetic pole and, the spacing between said first and second magnetic yokes is increased toward the rear portion, starting at a position corresponding to the magnetic gap depth from the second magnetic pole tip, to house said conductor coil and said insulating layer;
• said second magnetic pole of said second magnetic yoke has a width in the track width direction for recording a signal on a track width of said recording medium;
• said width keeps constant over a predetermined length toward the rear portion, starting at the second magnetic pole tip and spreads monotonically toward the rear, starting at a spread start position corresponding to the predetermined length from the second magnetic pole tip;
• and
• said predetermined length terminating in the spread start position of said width of said second magnetic yoke is shorter than said magnetic gap depth.