Ion beam modification of exchange coupling to fabricate patterned media

For bit-patterned media, media with low remanent magnetization (M _r) and high M _r regions are needed for storing information, which is usually achieved by lithographically defining magnetic and non-magnetic regions. In this work, we have investigated the use of ion beam modification of media surface to define the low and high M _r states using a medium that is at a low M _r state to start with. The low M _r state is achieved by the use of synthetic antiferromagnetic coupling obtained in Co-alloy/Ru/Co-alloy trilayer structured film. Local ion beam modification at 30 keV energy using Ga ions was used to create high M _r regions. AFM and MFM observations indicated that patterned regions of low and high M _r can be observed with ion beam irradiation. This technique is a potential method to achieve patterned media without the need of planarization techniques.