Composite media for high density heat assisted magnetic recording

A heat assisted magnetic recording composite media with a superparamagnetic writing layer is proposed. The recording process is initiated in the write layer that is magnetically softer than the long term storage layer. Upon cooling, the composite structure copies the information from the writing layer to the lower Curie temperature (Tc) storage layer, e.g., doped FePt. The advantages include insensitivity to Tc variance in the storage layer, and thus the opportunity to significantly lower the FePt Tc without the resulting Tc distribution adversely affecting the performance. The composite structure has a small jitter within 0.1 nm of the grain size limit owing to the sharp transition width of the optimized superparamagnetic writing layer. The user density of the composite structure can reach 4.7 Tb/in.2 for a Gaussian heat spot with a full-width-at-half-maximum of 30 nm, a 12 nm reader width, and an optimized bit length of 6 nm.