Magnetic property and microstructure dependence of CoCrTa/Cr media on substrate temperature and bias

Thin CoCrTa/Cr films were deposited at different substrate temperature T/sub s/ and substrate biasing voltage V/sub b/. The in-plane coercivity increased significantly with T/sub S/ and V/sub b/. Coercive squareness and orientation ratio also increased with T/sub s/ and V/sub b/. Transmission electron microscopy (TEM) results indicated that, at low T/sub s/, the magnetic film had an isolated-grain structure, with smaller sub-grain structure within each grain. At high T/sub s/, the magnetic film had a closely packed grain structure, probably due to the enhanced adatom mobility; the grain size was much larger and striations were observed in many grains. The application of a negative biasing voltage to the substrate also tended to reduce the grain isolation. At high T/sub s/, it seems that biasing also reduced the number of grains with striations. Scanning electron microscopy (SEM) results indicated that, with increasing T/sub s/ and V/sub b/, more high-frequency texture line appeared in the magnetic layer, which was likely related to the increase of orientation ratio and squareness with increasing T/sub s/ and V/sub b/.<
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