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An NiAl layer was introduced as a seed layer and as a domain wall pinning layer for Co-Pd multilayer perpendicular magnetic recording media. Grain size of the Co-Pd multilayer media was reduced significantly with the introduction of an NiAl seed layer. The angular dependence of the coercivity data indicated a domain wall pinning effect of the NiAl layer which was introduced into the Co-Pd multilayer media. Improvements were observed in read/write tests on a Co-Pd multilayer medium with an NiAl pinning layer. Index Terms--Co-Pd multilayer, NiAl pinning layer, NiAl seed layer, perpendicular media.

Medium noise from Co/Pd multilayer media prepared at different conditions have been studied For sputter-deposition preparation, a large transition noise was observed in the sample prepared at a sputtering Ar gas pressure of 1 Pa, and it was significantly reduced by raising the sputtering gas pressure to 70 Pa. For evaporation-deposition preparation, the main type of medium noise was the DC erase noise, and it was reduced by preparing the samples at higher pressure through introducing air. The above improvements in medium noise for sputter- and evaporation-deposited Co/Pd multilayer media were resulted from the reduction in the magnetic domain size when the gas pressures during preparation were increased.

Read-write tests and magnetic force microscopy (MFM) observations have been performed for Co/Pd multilayer perpendicular magnetic recording media. For a Co/Pd multilayer medium with a nucleation field ([H.sub.n]) of-1.5 kOe and a small slope at coercivity (He), no reversed magnetic domains between the transitions were observed and a low medium noise was also obtained. Moreover, a negligible time decay in magnetization was detected at the remanent state as well as in signals at both low and high recording densities. Index Terms--Co/Pd multilayer media, perpendicular magnetic recording, reversed magnetic domains, medium noise.