Weak dipolar interaction between CoPd multilayer nanodots for bit-patterned media application

The morphology and magnetic performance of CoPd multilayer nanodots have been investigated by a combination of DC sputtering, anodic aluminum oxide(AAO) template method and Ar ion etching. The nanodots exhibit a normal switching field distribution(SFD) of 17%, which is comparative to Bit-patterned media (BPM) made by e-Beam. It is found that the first-order reverse curve (FORC) data of CoPd nanodots have a good match with the mean-field model, which shows dipolar interaction contributes as small as 8.4% to the total SFD. Magnetic force microscope(MFM) imaging at a certain location confirms the FORC results by observing the effect of dipolar interaction directly. Our CoPd multilayer nanodots can be a good candidate for BPM application.