Abstract: Methods and media structures are provided for increasing writability and reducing unintentional erasure of perpendicular magnetic recording media. Variable permeability is controlled within a thin soft underlayer (SUL) structure, independent of bulk SUL material properties such as magnetic moment (Bs) and magnetic anisotropy (Hk). Media with an improved combination of easier writability on the recorded track and difficult erasure off-track (between tracks and on neighboring tracks) is achieved, in part, by an unbalanced antiferromagnetically coupled (AFC) SUL structure. A permeability gradient is established within the soft underlayer with layers having different values of permeability and magnetic thickness (Bs*t). In an aspect, a first SUL layer includes a high permeability region and an overlying low permeability region. A second layer antiferromagnetically couples the first layer to a low permeability third SUL layer.

Abstract: A perpendicular magnetic recording layer of a magnetic recording medium includes a plurality of bit-patterned magnetic islands, wherein each of the plurality of islands overlay a soft magnetic under-layer. Each of the magnetic islands includes a first magnetic sub-layer adjacent a second magnetic sub-layer, wherein the first sub-layer has a relatively high magnetic anisotropy that is greater than a magnetic anisotropy of the second sub-layer. The magnetic recording layer further includes a third sub-layer, which extends to connect each of the plurality of islands. The third sub-layer may have a magnetic anisotropy that is less than that of the second sub-layer of each of the magnetic islands and/or may serve as an interlayer, extending between the first sub-layer and the soft magnetic under-layer of the recording medium, and having a structure to help to produce the greater anisotropy first magnetic sub-layer.

Abstract: The present disclosure generally relates to a HAMR head and techniques and apparatus for HAMR writer pole length characterization. One or more bits may be magnetically written on a disk using a leading edge of the writer pole at a first polarity. The disk may be moved under a body of the writer pole to magnetically write the one or more bits in the disk at a second polarity that is opposite to the first polarity to generate a feedback pulse having a signal amplitude. The signal amplitude of the feedback pulse may be measured as a function of writing frequency. A first effective length of the writer pole may be determined based on the measurements.

Abstract: Systems and methods for providing heat assisted magnetic recording (HAMR) media configured to couple energy from a near field transducer (NFT) are provided. One such method includes providing a magnetic recording layer including an L10 ordered FePt or an L10 ordered CoPt, selecting a plurality of preselected parameters for a coupling layer, the preselected parameters including a material, a preselected deposition temperature, and a preselected thickness, and depositing the coupling layer directly on the magnetic recording layer using the preselected parameters such that the coupling layer has an extinction coefficient greater than 0.1.

Abstract: Methods and media structures are provided for increasing writability and reducing unintentional erasure of perpendicular magnetic recording media. Variable permeability is controlled within a thin soft underlayer (SUL) structure, independent of bulk SUL material properties such as magnetic moment (Bs) and magnetic anisotropy (Hk). Media with an improved combination of easier writability on the recorded track and difficult erasure off-track (between tracks and on neighboring tracks) is achieved, in part, by an unbalanced antiferromagnetically coupled (AFC) SUL structure. A permeability gradient is established within the soft underlayer with layers having different values of permeability and magnetic thickness (Bs*t). In an aspect, a first SUL layer includes a high permeability region and an overlying low permeability region. A second layer antiferromagnetically couples the first layer to a low permeability third SUL layer.

Abstract: A perpendicular magnetic recording layer of a magnetic recording medium includes a plurality of bit-patterned magnetic islands, wherein each of the plurality of islands overlay a soft magnetic under-layer. Each of the magnetic islands includes a first magnetic sub-layer adjacent a second magnetic sub-layer, wherein the first sub-layer has a relatively high magnetic anisotropy that is greater than a magnetic anisotropy of the second sub-layer. The magnetic recording layer further includes a third sub-layer, which extends to connect each of the plurality of islands. The third sub-layer may have a magnetic anisotropy that is less than that of the second sub-layer of each of the magnetic islands and/or may serve as an interlayer, extending between the first sub-layer and the soft magnetic under-layer of the recording medium, and having a structure to help to produce the greater anisotropy first magnetic sub-layer.