Patent ID: 7548400

Claim:
A thin-film magnetic head, comprising: a lower insulating layer; a magnetoresistive (MR) sensor formed on said lower insulating layer and comprising; a first ferromagnetic layer in which a magnetization direction is fixed with respect to external magnetic fields, a non-magnetic intermediate layer, and a second ferromagnetic layer in which a magnetization direction, changes with respect to the external magnetic fields; a pair of bias layers for exerting a bias magnetic field upon the MR sensor said bias layers extending substantially symmetrically from two sides of said MR sensor in a direction of track width of a recording medium, each bias layer being connected with said MR sensor over a length which is substantially the same as said MR sensor in a direction perpendicular to the air bearing surface, and each bias layer having a shape which is contained within an imaginary rectangle which has its long sides along said air bearing surface in the direction of the track width of the recording medium and its short sides in the direction perpendicular to said air bearing surface and which contacts the short side of the imaginary rectangle which is opposite the short side which contacts said MR sensor; a pair of lead layers for supplying said sense current to said MR sensor each extending from said air bearing surface to cover at least a portion of each of said bias layers; and an insulating layer formed on said lower insulating layer and contacting said pair of bias layers only on a side of said bias layers which is opposite the air bearing surface, an upper surface of the insulating layer being flush with an upper surface of the bias layers, wherein said pair of lead layers covers at least a portion of said pair of bias layers and said insulating layer, and wherein each of said bias layers has a shape which is contained within said imaginary rectangle in which a ratio of a length of said long sides to a length of said short sides is at least 5.