Patterned perpendicular magnetic recording medium with ultrathin oxide film and reduced switching field distribution

Abstract

A patterned perpendicular magnetic recording disk has a Co-alloy recording layer patterned into discrete data islands arranged in concentric tracks and exhibits a narrow switching field distribution (SFD). The disk includes a substrate, a NiTa alloy planarizing layer on the substrate, a nonmagnetic Ru-containing underlayer on the planarizing layer, an oxide-free Co alloy magnetic recording layer, and an ultrathin oxide film between the Ru-containing layer and the Co-alloy magnetic recording layer. The oxide film may be an oxide selected from a Ta-oxide, a Co-oxide and a Ti-oxide, and is ultrathin so that it may be considered a discontinuous film. The planarizing layer and ultrathin oxide film improve the growth homogeneity of the Co-alloy recording layer, so that the patterned disk with data islands shows significantly reduced SFD.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]This invention relates generally to patterned perpendicular magnetic recording media, such as disks for use in magnetic recording hard disk drives, and more particularly to patterned disks with data islands having improved magnetic recording properties.[0003]2. Description of the Related Art[0004]Magnetic recording hard disk drives with patterned magnetic recording media have been proposed to increase data density. In conventional continuous magnetic recording media, the magnetic recording layer is a continuous layer over the entire surface of the disk. In patterned media, also called bit-patterned media (BPM), the magnetic recording layer on the disk is patterned into small isolated data islands arranged in concentric data tracks. While BPM disks may be longitudinal magnetic recording disks, wherein the magnetization directions are parallel to or in the plane of the recording layer, perpendicular magnetic recording dis...

AI Technical Summary

Benefits of technology

[0008]The invention relates to a patterned perpendicular magnetic recording disk with a Co-alloy recording layer and a narrow SFD, and a disk drive incorporating the disk. The disk includes a substrate, an optional soft underlayer (SUL) of soft magnetically permeable material on the substrate, a planarizing layer on the substrate or optional SUL, a nonmagnetic Ru-containing underlayer on the planarizing layer, a perpendicular magnetic recording layer of a Co alloy that preferably contains no oxides, and an ultrathin oxide film between the Ru-containing layer and the Co-alloy magnetic recording layer. The recording layer is patterned into discrete islands arranged in concentric tracks. An optional NiW alloy seed layer may be located on the planarizing layer below and in contact with the Ru-containing underlayer. The planarizing layer is preferably a NiTa alloy with a thickness preferably greater than 20 nm, but if the optional SUL is present between the substrate and the planarizing layer, the planarizing layer can have a thickness between about 2 to 10 nm. The oxide film may be an oxide selected from a Ta-oxide, a Co-oxide and a Ti-oxide and having a thickness less than or equal to 1.5 nm. In this thickness regime, the oxide film thickness may be considered an “average” thickness of a discontinuous film, so that the surface onto which the Co-alloy magnetic recording layer is deposited may be both the Ru-containing layer and clusters or regions of the oxide film. The planarizing layer and ultrathin oxide film improve the growth homogeneity of the Co-alloy recording layer, so that a BPM with data islands according to the invention shows significantly reduced SFD.

Problems solved by technology

A critical issue for the development of BPM is that the switching field distribution (SFD), i.e., the island-to-island variation of the coercive field, needs to be narrow enough to insure exact addressability of individual islands without overwriting adjacent islands.

Additionally, it has been found that the SFD broadens (that is, the bit-to-bit variation in the coercive field increases) as the size of the magnetic islands is reduced, which limits the achievable bit areal density of BPM.

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