Possible noise mechanisms in perpendicular magnetic recording media were studied by experimental thin film model systems. Noise mechanisms considered include intergranular exchange coupling, interface anisotropy, and stacking faults. For each topic, MgO substrates are used to epitaxially grow Co and/or Co₈₄Pt₁₆ thin films with specific crystallographic orientation. Such highly oriented films are useful for understanding magnetic or structural properties of media that may not be possible to evaluate from media itself.

Intergranular exchange coupling was studied using Co₈₄Pt ₁₆/Oxide/Co₈₄Pt₁₆ trilayers to determine the strength of exchange coupling for several oxides of varying thickness. It was found that the coupling energy had an exponential dependence on oxide thickness that varied among different oxides. This coupling energy could be suppressed substantially by depositing a small amount of Cr at the CoPt/Oxide interface. Comparison of these experimental results with other micromagnetic modeling work indicates that intergranular exchange coupling will result in significant degradation of media signal-to-noise ratio when the grain size is smaller than ,9nrn unless grain boundary thickness is increased.

A series of Co/Oxide, Co/Cr, and CoPt/Cr multi-layers were used to evaluate the role of interface anisotropy in media. The calculated values of interface anisotropy in this model system represent a significant portion of the grain anisotropy in real media for grain sizes less than ,9nm. Other micromagnetic modeling shows that there will be a strong dependence of switching field on grain size if interface anisotropy exists and, consequently, a switching field distribution will originate from non-uniform grain size and morphology.

Stacking faults were evaluated by a combined set of experimental and simulated diffraction studies. Broadening of diffraction profiles was used to quantitatively evaluate stacking fault content in (00.1) oriented Co and Co₈₄Pt₁₆ thin films. Stacking fault density is found to decrease with increasing growth temperature concurrent with an improvement in magnetic anisotropy, K_u, and compression of the lattice parameter, c. Pure cobalt tends to grow with a larger average stacking fault size than Co₈₄Pt₁₆, but with a lower density. The strong dependence of magnetic anisotropy on crystallographic aspects further underscores the need for crystallographic uniformity in media.