Patent ID: 8709618

Claim:
A magnetic storage apparatus including a perpendicular magnetic recording medium, a magnetic recording medium driver for driving the perpendicular magnetic recording medium in a recording direction, a magnetic head having a recording unit and a read element, a magnetic head driver for relatively driving the magnetic head to the perpendicular magnetic recording medium, and a signal processing unit for processing input signals and output signals to the magnetic head in which the recording unit of the magnetic head has a main pole, an auxiliary pole, and a magnetic shield disposed at least on the trailing side of the main pole via a non-magnetic gap layer, the perpendicular magnetic recording medium has a first recording layer having a granular structure comprising grain boundaries containing an oxide and columnar grains comprising a CoCrPt alloy, a second recording layer formed over the first recording layer, and a third recording layer formed directly on the second recording layer, the second recording layer and the third recording layer comprise Co as a main ingredient, contain Cr and do not contain an oxide, and the Cr concentration in the second recording layer is lower than the Cr concentration in the third recording layer, wherein t2/(t2+t3) is 0.1 or more and 0.4 or less in which t2 is a thickness of the second recording layer and t3 is a thickness of the third recording layer.