HAMR Emulation on Carbon Overcoat and Lubricant for Near Field Transducer and Magnetic Media Using Surface-Enhanced Raman Sensors

A plasmonic sensor is used for emulation of near field transducer (NFT). Some overcoat films (thickness of 1nm) were coated on Au nanoparticles (NPs) on a convex quartz glass substrate (plasmonic sensor). Heating behavior of the films was examined by laser heating using novel Raman spectroscopic tools, i.e. surface-enhanced Raman scattering (SERS) with the plasmonic sensor, a continuous laser heating tool, in-situ observation of spectra and temperature with a high speed time-resolved measurement. The heating temperature of tetrahedral carbon (ta-C) film in He gas is lower than that in air. This is because the thermal conductivity of He is larger than air. Few spectral change of ta-C film (thickness of 1nm) on Au NP’s is observed except initial change in around 100 s at the temperature around 500 °C, which corresponds to the temperature of the carbon overcoat (COC) for the media temperature of 327 °C (600K, Currie temperature for CoPt alloy). Some carbide films, i.e. SiC, TiC, and WC, showed high heat resistance, that is, few spectral change was observed. It is found that lubricant is evaporated from the COC on magnetic media and transferred to the plasmonic sensor.