AVS 49th International Symposium
    Magnetic Interfaces and Nanostructures Wednesday Sessions
       Session MI-WeM

Invited Paper MI-WeM1
Perpendicular Recording Media Near 100 Gbit per square inch

Wednesday, November 6, 2002, 8:20 am, Room C-205

Session: Magnetic Recording: GMR, Tunneling, and Media
Presenter: D. Weller, Seagate Research
Authors: D. Weller, Seagate Research
B. Lu, Seagate Research
Y. Kubota, Seagate Research
J. Ahner, Seagate Research
G. Ju, Seagate Research
X. Wu, Seagate Research
D. Karns, Seagate Research
A. Sunder, Seagate Research
C.H. Chang, Seagate Recording Media Operations
C. Brucker, Seagate Recording Media Operations
R. Ranjan, Seagate Recording Media Operations
M. Kryder, Seagate Research
Correspondent: Click to Email
Media noise suppression via reduced grain and magnetic cluster size and at the same time thermal stability are general requirements to advancing magnetic recording technology to higher areal densities, beyond 100 Gbit per square inch. In perpendicular recording, using a hard/soft dual layer media scheme, one seeks to use magnetically harder media. Such media sustain smaller stable grains and can be written owing to the improved write field geometry that perpendicular pole heads in conjunction with soft magnetic underlayers offer over the conventional ring head geometry used in longitudinal recording. Modeling suggests, that this technology is extendible to areal densities of the order of Terabit per square inch. In this paper, we review current-state-of the art perpendicular media and review testing results near 100 Gigabit per square inch recording densities. The key challenges relate to controlling average grain sizes and their distributions as well as intergranular exchange coupling in the hard layer and at the same time generating a low noise, high permeability soft magnetic underlayer. We have fabricated both CoPtCr-type alloy and CoCr/Pd-type multilayer media and obtained grain sizes of D=10.5+/-2.2nm and D=13.1+/-2.5 nm, respectively. These media have full remanence squareness (S=1), negative onset fields for reversal > 2000 Oe, thicknesses in the range 10-18 nm and are thermally stable. The soft underlayer material is an amorphous FeCoB alloy with 1.9 T flux density and a static permeability of >400; it is stabilized into a single domain, noise free state, via an induced radial magnetic anisotropy field > 50Oe. The spacer between the soft underlayer and hard layer is an alloy seed layer structure of total thickness less than 5 nm. This interlayer controls the microstructure of the subsequent recording layer and is key to enhancing the performance of perpendicular media.