Patent ID: 7957097

Claim:
A magnetic head for perpendicular magnetic recording comprising: a medium facing surface that faces toward a recording medium; a coil for generating a magnetic field corresponding to data to be written on the recording medium; a pole layer allowing a magnetic flux corresponding to the magnetic field generated by the coil to pass therethrough and generating a write magnetic field for writing the data on the recording medium by means of a perpendicular magnetic recording system; and an encasing section that accommodates at least part of the pole layer, wherein: the encasing section includes: an encasing layer made of a nonmagnetic material and having an encasing groove that opens in a top surface of the encasing layer and that accommodates the at least part of the pole layer; and a nonmagnetic film made of a nonmagnetic material and disposed in the encasing groove at a position between the encasing layer and the pole layer; the pole layer includes: a track width defining portion having an end face located in the medium facing surface and an end opposite to the end face; and a wide portion connected to the end of the track width defining portion and having a width greater than that of the track width defining portion; the end face of the track width defining portion located in the medium facing surface defines a track width; a distance from the medium facing surface to a boundary between the track width defining portion and the wide portion is within a range of 10 to 300 nm; the track width defining portion has a first side surface and a second side surface; the wide portion has a third side surface contiguous to the first side surface, and a fourth side surface contiguous to the second side surface; the encasing layer has a first wall surface and a second wall surface that form the encasing groove, the first wall surface is opposed to the first and the third side surface, and the second wall surface is opposed to the second and the fourth side surface; the nonmagnetic film includes a first portion located between the first side surface and the first wall surface, and a second portion located between the second side surface and the second wall surface; and a distance between the third side surface and the first wall surface is smaller than a distance between the first side surface and the first wall surface, while a distance between the fourth side surface and the second wall surface is smaller than a distance between the second side surface and the second wall surface.