Wd Media (Singapore) Pte. Ltd.

Chiyo Saito

Iwao Okamoto

Daisuke Masuda

Junichi Horikawa

Takenori Kajiwara

Tokichiro Sato

An object of the present invention is to further improve a recording density in a magnetic disk apparatus using a shingle write system. In a magnetic disk apparatus including a magnetic disk, a recording head that writes information on the magnetic disk, and a controller that controls a writing operation of the recording head to the magnetic disk, the controller controls the writing operation such that the recording head writes information on a region including a target track and a portion of track adjacent thereto in an overlapping manner while position-shifting in a radial direction of the magnetic disk and a first writing frequency to a track on which information is last written is higher than a second writing frequency to another track.

Apparatus of single write magnetic disc

Provided are a magnetic disk comprising a granular magnetic recording layer which causes less noise even with a recording capacity thereof of 250 G or more bits per square inch; and a method for manufacturing the same. The magnetic disk according to the present invention comprises: a granular magnetic recording layer () which is formed on a disk substratedirectly or via an intermediate layer and which has non-magnetic regions between granular columnar particles; and an auxiliary recording layer () which is formed on the granular magnetic recording layerand which causes exchange interaction among the granular columnar particles, wherein the auxiliary recording layer () contains 0.1 to 3 moles of oxygen.

Magnetic disk and method for manufacturing same

A characteristic evaluation method of a perpendicular magnetic recording medium suitable for obtaining a perpendicular magnetic recording medium which can respond to much higher recording density is provided. This is an evaluation method of a perpendicular magnetic recording medium, including a process of recording a first signal of a specific frequency at an arbitrary first position in the perpendicular magnetic recording medium; a process of measuring a reproduction output of the first signal and of measuring a signal/noise ratio (initial value) of the first signal at a peak position where the reproduction output becomes the maximum; a process of recording a signal of a specific frequency at a second position away from the first position by a predetermined distance in the radial direction of the perpendicular magnetic recording medium; a process of measuring the signal/noise ratio of the first signal at the peak position again; a process of repeating the process of recording the signal of the specific frequency at a position brought close to the first position from the second position by a predetermined distance and of measuring the signal/noise ratio of the first signal at the peak position again while sequentially getting closer to the first position from the second position; and a process of determining whether the value of the signal/noise ratio has lowered from the initial value by a predetermined range or more.

Evaluation method of perpendicular magnetic recording medium and manufacturing method of perpendicular magnetic recording medium

[Problem] A perpendicular magnetic recording medium and a magnetic disk device that are suitable for a shingle recording type are provided. [Solution] The perpendicular magnetic recording medium of the present invention is a perpendicular magnetic recording medium for a shingle recording type having a laminated film including a soft magnetic layerand a main recording layerformed on base, the soft magnetic layerhaving a thickness found from a core width of a magnetic head for recording and reproduction with respect to the perpendicular magnetic recording medium and a track pitch narrower than the core width.

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Tokyo, Japan

Chiyo Saito