I. Introduction
Heat-assisted magnetic recording (HAMR) makes use of temperature-dependent changes in the magnetic storage layer to enhance the writing process and thereby increase the ultimate areal density capacity of the storage medium. This new technology will use plasmonic structures located within the read-write head to create ultra-small sub-diffraction limited spots on the media that transiently heat the magnetic film within a well-defined area. The controlled heating of the media surface must take place for a defined time and to a fixed target temperature to allow the formation of a sufficient thermal gradient (within the media) to enhance the writing process [1]. The HAMR media films, and their response to the evanescent field emanating from the near-field transducer (NFT), must be designed with consideration, not only of its magnetic properties but also, just as important, their optical and thermal properties to obtain this significant enhancement in HAMR writing. Thus, the optical properties of the entire media film structure, at least up to the penetration depth of the evanescent field, are important for successful heat-assisted recording.