Heat-Assisted Magnetic Recording’s Extensibility to High Linear and Areal Density

Heat-assisted magnetic recording (HAMR) is being developed as the next generation magnetic recording technology. Critical components of this technology, such as the plasmonic near-field transducer and high anisotropy granular FePt media, as well as recording demonstrations and fully integrated drives have been reported. One of the remaining ongoing challenges of magnetic recording in general and HAMR in particular has been the demonstration of high linear density recording, approaching the grain-size (GS) limit of the recording media, and a clear pathway to smaller GSs while maintaining good magnetic properties and distributions. This paper will demonstrate the extensibility of FePt-based media down to the 5 nm center-to-center range. A linear recording density of 3000 kilobits per inch (kbpi), or a bit length of 8.5 nm, approaching the GS limit of this media, has been demonstrated on recording media with a slightly larger GS of 7 nm center-to-center, and using an HAMR head with high thermal gradient >10 K/nm. Key parameters of the media include the microstructure, the thermal design and magnetic properties, most importantly the tradeoff between achievable GS, media moment-thickness product, Mrt, and the distributions of the magnetic switching field and the Curie temperature. Further optimizing the composition, growth, and architecture of the media stack to achieve all the prerequisite magnetic and thermal properties for high signal-to-noise ratios in the smallest demonstrated GS media allows linear recording densities of up to 4000 kbpi, and areal densities in the 3-4 tera-bits-per-square-inch range can be extrapolated based on geometrical scaling.