摘要 :
We report a systematic study of the switching and recording characteristics of perpendicular magnetic recording media in which the exchange coupling between granular oxide and continuous cap layers was varied. The interfacial exc...
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We report a systematic study of the switching and recording characteristics of perpendicular magnetic recording media in which the exchange coupling between granular oxide and continuous cap layers was varied. The interfacial exchange coupling strength was controlled by adjusting the magnetization $({rm M}_{rm s})$ and the thickness (t) of the exchange control layer (ECL) between granular oxide and cap layers. The media switching mechanism highly depends on the oxide-to-cap exchange coupling strength as well as the relative moment ratio of cap and oxide layers. Reversal process is coherent for medium with only granular oxide layer and becomes incoherent with incorporation of ECL and continuous cap layers. Optimizing granular oxide-to-cap exchange coupling improves the media writeability as well as the media signal-to-noise ratio $({rm SNR}_{rm m})$. At optimum exchange coupling condition, the switching field is significantly reduced even with higher thermal stability factor (${rm K}_{rm u} {rm V/k}_{rm B}$ T). However, when the interlayer coupling strength is too weak, independent switching of oxide and cap layers occurs, resulting in poor writeability and high media noise. An optimum design of oxide-to-cap exchange coupling is critical in attaining recording properties for high density recording through selection of appropriate ECL and cap materials.
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摘要 :
Variations of in-plane magnetic properties are observed in most commercial thin-film media. Magnetic anisotropies of varied origins give rise to preferred orientations quantified by the term orientation ratio (OR). Several mechani...
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Variations of in-plane magnetic properties are observed in most commercial thin-film media. Magnetic anisotropies of varied origins give rise to preferred orientations quantified by the term orientation ratio (OR). Several mechanisms for in-plane anisotropy have been proposed. Oblique angle of incidence effects from vacuum deposition can lead to the formation of tilted columnar or curved grains resulting in a strong shape anisotropy. The most effort has been involved in understanding 'scratch' anisotropy in textured media where OR develops along texture lines. Mechanisms involving stress, preferred orientation, circumferential alignment of grain c-axes, and radial out of plane c-axis effects have been proposed. Recent experiments and calculations suggest that isotropic media, (OR=1), are superior in signal to media noise, S/N/sub m/, at high recording densities. It is thus important to understand the origin of in-plane anisotropies in thin-film media so as to control them for possible recording property improvements or eliminate them altogether to achieve an isotropic media.
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摘要 :
The thermal stability of data stored in thin film recording media is closely tied to signal-to-noise ratio (SNR), yet is not correlated in a simple way. Indeed grain size strongly affects both SNR and thermal stability, but macros...
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The thermal stability of data stored in thin film recording media is closely tied to signal-to-noise ratio (SNR), yet is not correlated in a simple way. Indeed grain size strongly affects both SNR and thermal stability, but macroscopic magnetic properties as well as recording conditions are equally influential. This is illustrated by measurements of SNR and signal thermal decay along with a simple model analysis. Dependence of areal density on key magnetic properties, under SNR and stability constraints, is formulated.
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