Simulation on temperature rise using ring-resonator-type device for heat-assisted magnetic recording

Heat-assisted magnetic recording (HAMR) is a promising technology for improving the recording density of hard disk drives. A near-field transducer (NFT), which forms a small light spot on a recording medium, is necessary in HAMR. The authors’ group previously proposed a novel device, in which a metal nano-antenna acting as an NFT is attached to a semiconductor ring resonator acting as a light source via a dielectric spacer. In this study, the temperature rise including the recording medium using this device was analyzed through the combination of optical and thermal simulations. To reduce the temperature rise of the nano-antenna while heating the recording layer to the Curie temperature, the following two methods were used: first, the nano-antenna length and the spacer thickness were optimized. Second, a heat spreader, which surrounds the nano-antenna, was introduced. The nano-antenna was made of Au, and the spacer and heat spreader were made of SiO₂. When the peak temperature of the recording layer was 800 K, the temperature of the nano-antenna was 3350 K without the above methods, but it was significantly reduced to 400 K with the above methods. This is a sufficiently low value to keep the hardness of the nano-antenna. On the other hand, the thermal spot size in the recording layer was slightly increased from 62 × 64 nm² to 67 × 72 nm² by the above methods.