Illustration of grains, the randomness of easy-axis orientations and the bit boundary.
Epitaxial growth of Co(110) planes on Cr(200) planes in longitudinal recording medium.
The randomness of easy axis orientation: (a) three-dimensional (3D) random, (b) two-deminsional (2D) random, (c) oriented media, and (d) ideal orientation.
Trend of and as a function of areal density in longitudinal recording technology.
Bit boundary in longitudinal recording for three cases: (a) decoupled grains with negligible exchange coupling, (b) magnetic clusters with moderate exchange coupling, and (c) domain wall motion reversal mechanism.
Illustration of grains in magnetic recording media (a) with narrow grain boundary, (b) with broader nonmagnetic grain boundary, and (c) illustration of a grain with a magnetic core and nonmagnetic grain boundary.
The energy levels (for different applied fields) associated with a magnetic particle that switches coherently (as per the Stoner-Wohlfarth model).
Illustration of magnetic charges and the associated demagnetizing fields for longitudinal and perpendicular recording (a) thin film, (b) low density, and (c) high density. The arrows indicate the direction of demagnetizing field. Block arrows are used to show the higher strength of demagnetizing field.
Writing process in (a) longitudinal and (b) perpendicular recording. In perpendicular recording technology, the medium is virtually placed in the pole gaps between the head and the mirror image in SUL.
Different functional layers of perpendicular recording medium with approximate thickness (layers are not to scale).
Illustration of 180° domain formation in SUL and an enlarged view of a transition.
Magnetization of two layers of antiferromagnetically coupled SUL during the writing and reading (remanence).
(Color online) Mapping of noise pattern of SUL with a spin-stand and a read-write head: (a) single SUL and (b) antiparallelly coupled SUL.
Illustration of (a) typical layers of current perpendicular recording media, (b) heteroepitaxial growth, and (c) design that involves dual Ru layers.
(Top) Illustration of remanence magnetization state of grains of perpendicular media after it was saturated with a field into the plane. (a) Grains with a lower anisotropy constant show a reversal with remanent magnetization out of the plane showing instability. (b) Grains with a higher anisotropy constant show stable magnetization. (Middle) Illustration of hysteresis loops of the respective media that show (c) a positive and (d) a negative (bottom) hysteresis loop with relevant parameters.
TEM planar view of a typical perpendicular recording medium.
Illustration of (a) media layer structure and (b) epitaxial growth of Ru and recording layer on crystalline FeCo SUL.
Layer structure of media in (a) conventional perpendicular media with dual Ru layers and (b) advanced media with a magnetic intermediate layer.
TEM planar view of grains in (a) RuCr intermediate layer and (b) RuCr-oxide intermediate layer.
Grain size distribution in media deposited (a) RuCr intermediate layer and (b) RuCr-oxide intermediate layer.
Properties of some soft magnetic materials.
List of intermediate layers (ILs) in the earlier days of perpendicular recording.
Approximate requirements for high-density recording media and how they are related to the recording performance (in current products and for approximately areal density).
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