Patent ID: 7583478

Claim:
A thin-film magnetic head comprising: a medium facing surface that faces toward a recording medium; a magnetoresistive element disposed near the medium facing surface and having a first surface and a second surface that face toward opposite directions and that intersect the medium facing surface, the magnetoresistive element reading data stored on the recording medium by means of a perpendicular magnetic recording system; a first read shield layer disposed to face toward the first surface of the magnetoresistive element; a second read shield layer disposed to face toward the second surface of the magnetoresistive element; and bias field applying layers for applying a bias magnetic field to the magnetoresistive element, wherein: each of the first and second read shield layers has: a first end face located in the medium facing surface; a second end face opposite to the first end face; a first width changing portion that continuously decreases in width as a distance from the first end face decreases; and a second width changing portion that continuously decreases in width as a distance from the second end face decreases; each of the first and second read shield layers has such a plane geometry that four corners of a circumscribed rectangle that circumscribes the plane geometry are cut off; and assuming that, among four pieces separated from the circumscribed rectangle to form the plane geometry, two of the pieces closer to the first end face are defined as first pieces while the other two of the pieces closer to the second end face are defined as second pieces, and that the plane geometry and the circumscribed rectangle are folded along an imaginary center line parallel to the medium facing surface, a value obtained by dividing an area of portions of the first and second pieces that are not laid over each other by a sum of areas of the first and second pieces falls within a range of 0 to 0.2 inclusive.