Microstructural investigations of CoCrPtICr andCoCrPt/CrV magnetic thin film media were conducted in order to explain improved media performance as a function of increased Cr concentration in the magnetic layer and a predeposition treatment of the Nip plated AI substrate. Using High Resolution Transmission Electron Microscopy (HRTEM) and Selected Area Diffraction Patterns (SADP) it was found that for both underlayer structures, no significant microstructural differences (such as grain size, stacking fault density, orientation, crystalline phase, and bi-crystals) exist between samples grown with 13% Cr and 22% Cr. This indicates that Cr segregation to grain boundaries is the most likely mechanism for improved S/N ratio and higher coercivity. The increased coercivity observed in the treated samples is consistent with an increased grain size in the magnetic layer due to larger Cr underlayer grains

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Dot-by-dot analysis of magnetization reversal in perpendicular patterned CoCrPt medium by using magnetic force microscopy

The further development of computer hard disk technology involves ever increasing density of information storage. Current levels of recording are about 1 Gbit per square inch, which will increase by a factor often over the next couple of years. The methodology is well-established: ferromagnetic cobalt alloy thin films (≈20 nm) are sputtered onto an appropriate substrate. Improvement in the magnetic performance (e.g., coercivity, signal-to-noise) requires manipulation of the microstructure by the deposition conditions. Transmission electron microscopy (TEM) is really the only characterization tool which can yield all the necessary information (structural, chemical and magnetic) because of the dimensions involved (e.g., grain sizes of 10-20 nm, with grain boundary segregation an important consideration). This article illustrates some recent contributions to understanding the structure-property-processing combination in this rapidly developing area.The typical hard disk is made up from an aluminum alloy substrate, a 5-10 micron thick, hard NiP electrodeposited layer, a chromium underlayer, the magnetic Co alloy and a protective thin carbon overcoat.

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