Patent ID: 8085499

Claim:
A magnetic disk drive including a magnetic recording medium, a perpendicular magnetic recording head, and a positioning device for positioning the perpendicular magnetic recording head over the magnetic recording medium, said magnetic disk drive supplying write electrical current to the perpendicular magnetic recording head, said perpendicular magnetic recording head comprising: a main pole including a magnetic multilayer composed of a high saturation flux density layer and a low saturation flux density layer; a return path for supplying a magnetic flux to the main pole; and a conductive coil for excitation of the return path, wherein: the high saturation flux density layer contains an Fe-Co alloy, a width of the main pole is 200 nanometers or less, a direction of magnetization in a pair of the high saturation flux density layers of the magnetic multilayer facing each other with respect to the low saturation flux density layer is oriented in an antiparallel arrangement by magnetostatic coupling between magnetization of the high saturation flux density layers, a thickness of the high saturation flux density layer is thicker than the thickness of the low flux density layer, and a thickness of the high saturation flux density layer formed nearest from a slider substrate and a thickness of the high saturation flux density layer formed farthest from the slider substrate is thinner than a thickness of the high saturation flux density layer formed between said two high saturation flux density layers.