Optical modeling of media for heat assisted magnetic recording

The validity of effective medium theory for modeling nanocomposite thin films interacting with a plasmonic nanoantenna has been investigated using an optical circuit model and finite-difference time-domain simulations. We show that in the regime where the size of the optical beam generated by the nanoantenna is comparable to the feature size inside the thin film, the effective medium theory is not valid anymore. We demonstrate that using effective medium theory can cause a dramatic error in the performance analysis of applications such as heat assisted magnetic recording that work at this regime. Therefore, we develop a theoretical framework based on circuit theory at optical frequencies to study and design nanocomposite thin films for these applications. (C) 2016 AIP Publishing LLC.