Antiferromagnetically Coupled Patterned Media and Control of Switching Field Distribution

Switching Field distribution (SFD) is one of the critical issues for writing in bit patterned media (BPM) for high areal densities. It is believed that the magnetostatic interaction is one of the several factors that contribute to the SFD. With the antiferromagnetically coupled (AFC) structure, the magnetostatic interaction can be tailored to understand/reduce SFD. In this study, AFC patterned media is studied with emphasis placed on the effect of the top layer coercivity, which will determine the M_r and hence the magnetostatic interaction. For this study, nanodots with a size and space of 60 and 40 nm respectively were fabricated with electron beam lithography (EBL). Remanent hysteresis curves for the nanodot arrays were obtained by counting the number of reversed dots in magnetic force microscopy (MFM) images at remanent state. The narrowest SFD at a pressure of 1 Pa for top layer was observed possibly because of good crystaline texture and reduced magnetostatic interaction.