Reduction of recording noise caused by nano-scale variations in Curie temperature

Heat-Assisted Magnetic Recording (HAMR) is expected to be the next-generation magnetic recording technology: it is designed to meet increasing higher areal density demands from cloud storage. Until now, there are no feasible solutions to address nm-scale Curie temperature variance in FePt-based single layer media. This variance is the leading noise source, and thus limits further development of HAMR technology. Here, we describe a superparamagnetic write process that can greatly mitigate the impact of Curie temperature variance by recording information at the blocking temperature of the magnetic material. To demonstrate the benefits of this write process, we employ a bilayer structure with a superparamagnetic write layer and FePt as a long-term storage layer. By developing the theory behind the recording mechanism, we are able to introduce design rules addressing the importance of elevated Curie temperature in the write layer and optimization of quantum mechanical coupling between the two functional layers.