Hitachi Global Storage Technologies Netherlands B.v.

Bernd Heinz

Yoshihiro Ikeda

Kentaro Takano

Hoa Van Do

Min Xiao

Qing Dai

Mary Frances Minardi

A perpendicular magnetic recording disk has a soft magnetic underlayer (SUL) that has high corrosion resistance as well as high moment. The material of the SUL is an alloy comprising Co, Fe, X, and Y; where X is Ta or Nb, Y is Zr or Hf, and the combined amount of X and Y present in the alloy is between about 10 and 20 atomic percent. The atomic ratio of Co to Fe in the alloy is between about 90:10 to 10:90, preferably between about 25:75 and 35:65. The SUL may be a single-layer SUL or a multilayer SUL formed of multiple soft magnetic layers separated by an interlayer film or films.

Perpendicular magnetic recording system and medium with high-moment corrosion-resistant 'soft' underlayer (SUL)

A perpendicular magnetic recording disk has a granular Co-based ferromagnetic alloy recording layer (RL) with oxides of a selected metal (Ta or Nb) and a reduced-thickness exchange-break layer (EBL) between the RL and the soft magnetic underlayer (SUL). A perpendicular magnetic recording system that includes the disk, the write head and the read head, has an improved ability to write to the RL because of the reduced-thickness EBL.

Perpendicular magnetic recording disk with recording layer containing selected metal oxides and formed on a reduced-thickness exchange-break layer

A perpendicular magnetic recording disk has an improved recording layer of a granular CoPtCr-based ferromagnetic alloy with inter-granular material made up of one or more oxides of Cr and one or more oxides of one or more of a segregant of Si, Ta, Ti, B, Nb or Hf, wherein the amount of oxygen present in the recording layer is greater than about 22 atomic percent and less than about 35 atomic percent. The amount of oxygen in the recording layer is substantially greater than the amount required for the stoichiometric oxide or oxides of the segregant or segregants, and a substantial portion of the oxygen present in the recording layer is present in the inter-granular material. The recording layer exhibits high signal-to-noise ratio (SNR), a coercivity Hgreater than about 5000 Oe and a nucleation field Hgreater (more negative) than about &#x2212;1500 Oe.

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Bernd Heinz