Next-generation heat-assisted magnetic recording (HAMR) relies on fast, localized heating of the magnetic medium during the write process. Au plasmonic near-field transducers are an attractive solution to this challenge, but increased thermal stability of Au films is required to improve long-term reliability. This work compares the effect of nanoscale Al, AlO x , and Ta capping films on Au thin films with Ti or Ta adhesion layers for use in HAMR and other high-temperature plasmonic applications. Thermal stability is investigated using a bespoke laser dewetting system, and SEM and AFM are extensively used to interrogate the resulting dewet areas. The most effective capping layers are found to be 0.5–1 nm of Al or AlO x , which can eliminate dewetting under certain conditions. Even one monolayer of AlO x is shown to be highly effective in reducing dewetting. In the case of thicker capping layers of Ta and AlO x , the Au film can easily dewet underneath, leaving an intact capping layer. It is concluded that thinner capping layers are most effective against dewetting as the Au cannot dewet without breaking them and pulling them apart during the dewetting process. A simple model based on energetics considerations is developed, which explains how thinner capping layers can more effectively protect the metal from pore or fissure creation. The model provides some convenient guidelines for choosing both the substrate and capping layer, for a given metal, to maximize the resistance to laser-induced damage.
We proposed a new elliptical near-field transducer (NFT) and V-shaped waveguide design, which provides multiple pathways to control and optimise the thermal performance of the optical delivery paths for heat-assisted magnetic recording (HAMR). The principle of operation of the design utilises the properties of the localised surface plasmon resonance (LSPR) of the metallic elliptical NFT. We demonstrated a peak temperature in the recording media normalised to the incident laser power (T Media /P In ) ranging from ∼ 128 K/mW to more than 181 K/mW. We also achieved tunable thermal gradients as high as 23.0 K/nm and 18.7 K/nm in the recording media’s down-track and cross-track directions, respectively. Moreover, we exemplified that the inevitable temperature rise in the plasmonic NFT could be tuned to remain under 400 K for maximum heat in the recording media > 700 K. The best thermal performance obtained corresponded to the aspect ratio of the antenna a/b ∼ 0.89 with the minor axis of the antenna a = 85 nm.
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