Abstract: Embodiments of the present invention provide a perpendicular magnetic recording medium having a substrate, a magnetic recording layer and a protective layer. The magnetic recording layer includes a perpendicular recording layer, a magnetic coupling layer and a writing assist layer. The perpendicular recording layer is a Co alloy layer containing an oxide disposed between the magnetic coupling layer and the substrate. The magnetic coupling layer is a ferromagnetic layer disposed between the perpendicular recording layer and the writing assist layer. The writing assist layer is a ferromagnetic layer disposed between the magnetic coupling layer and the protective layer. The saturation magnetization of the magnetic coupling layer is lower than the saturation magnetization of the perpendicular recording layer or the writing assist layer. The thickness of the magnetic coupling layer is 1 nm or more and 3 nm or less.

Abstract: Embodiments of the present invention provide a perpendicular magnetic recording medium suitable for high density recording. According to one embodiment, a magnetic recording layer comprises four layers in which a first magnetic layer, a magnetic coupling layer, a second magnetic layer, and a third magnetic layer are formed above a substrate. The first magnetic layer and the second magnetic layer are perpendicular magnetization films containing an oxide, and ferromagnetically coupled with each other by way of the magnetic coupling layer, and they are, more preferably, a Co alloy layer containing an oxide. The third magnetic layer is ferromagnetically coupled with the second magnetic layer. The concentration of the oxide contained in the third magnetic layer is lower than the concentration of the oxide in the second recording layer, or the third magnetic layer does not contain the oxide.

Abstract: Embodiments of the present invention provide a perpendicular magnetic recording medium having an improved writing property due to the exchange spring effect and capable of stable production. According to one embodiment, a perpendicular magnetic recording medium includes a non-magnetic substrate; an adhesion layer; a soft magnetic underlayer; a seed layer; and intermediate layer; a magnetic recording layer at least including a perpendicular recording layer, a writing assist layer, and a magnetic coupling layer disposed between the perpendicular recording layer and the writing assist layer; a protective layer, and a lubrication layer, in which the saturation magnetization of the magnetic coupling layer is lower than the saturation magnetization of the writing assist layer, the saturation magnetization of the magnetic coupling layer is 300 kA/m (300 emu/cc) or lower, and the thickness of the magnetic coupling layer is 1 nm or more and 3 nm or lower.