L10 FePt-based thin films for future perpendicular magnetic recording media

Current magnetic recording media using perpendicular CoCrPt-Oxide granular films are reaching their physical limit (approx 750 Gbit/in2 density) due to thermal fluctuations that hinder a further reduction of grain size (<6-7 nm) needed to scale down the bit size. L10-FePt alloy is currently considered the most promising candidate for future recording media with areal densities above 1 Tbit/in2 thanks to its high magneto-crystalline anisotropy (K=6-10 MJ/m3), which enables it to be thermally stable even at grain sizes down to 3 nm. However, its huge anisotropy implies an increase of the switching field, which cannot be afforded by current available write heads. To simultaneously address the writability and thermal stability requirements, exchange coupled composite media, combining two or multiphase hard and soft materials, where the hard phase provides thermal stability and the soft phase reduces the switching field, have been recently proposed. This paper briefly reviews the fundamental aspects as well as both experimental approaches and magnetic properties of L10 FePt-based single phase films and exchange coupled systems for future perpendicular magnetic recording media.