Nanocavity induced light concentration for energy efficient heat assisted magnetic recording media

Enhancing light absorption in the recording media layer can improve the energy efficiency and prolong the device lifetime in heat assisted magnetic recording (HAMR). In this work, we report the design and implementation of a resonant nanocavity structure to enhance the light-matter interaction within an ultrathin FePt layer. In a Ag/SiO₂/FePt trilayer structure, the thickness of the dielectric SiO₂ layer is systematically tuned to reach maximum light absorption at the wavelength of 830 nm. In the optimized structure, the light reflection is reduced by more than 50%. This results in effective laser heating of the FePt layer, as imaged by an infrared camera. The scheme is highly scalable for thinner FePt layers and shorter wavelengths to be used in future HAMR technologies.