The GOALI partnership between Carnegie-Melon University (CMU) and and Seagate Technology makes the research directly applicable to development of new technologies in the data storage industry. The next generation of high-density storage will be enabled by laser-excited near field transducers (NFTs) that focus electromagnetic energy onto thermally-activated nanometer-scale magnetic bits. Heat fluxes in excess of 100 times that present at the sun's surface at the functional end of an NFT can result in excessive operating temperatures. Similar limitations pervade plasmonics used for chemical catalysis, bio-sensing, and steam generation. Further, the proposed in-situ measurement of the interface temperature will enable entirely new metrology of plasmonic structures, and represents a step towards near field thermoreflectance metrology.
The educational activities will expose students to industry-driven academic research through curriculum development, guest lectures and seminars, and potential internships at Seagate. Seagate, in turn, will receive exposure at CMU through integration of the research topics and results within courses taught by the academic PIs.
The technical objective of this GOALI proposal is to experimentally study tradeoffs in heat dissipation and optical performance at plasmonic interfaces modified by nanoscale adhesion layers. The interdisciplinary research team will study the nature of plasmonic resonance, electron-phonon coupling, and phonon transmission in metal-dielectric interfaces with metal adhesion layers. Open scientific questions include: how do adhesion layers influence the physics of phonon transmission across a metal-dielectric interface and plasmonic resonance at the interface? Can the temperature dependence of plasmonic resonance be used to make in-situ measurements of interface temperature and thermal properties? To answer these questions, the research will investigate transport in prototypical Au/SiO2 and Au/AlN plasmonic interfaces with Cu, Ti, Al, Cr, and Be adhesion layers as a function of thickness from 1-5 nm. Relative to Au, these metals have successively better electron-phonon coupling and vibrational alignment with the dielectrics. Thin film samples will be sputtered and imaged by TEM. Thermal interface conductance will be measured using two independent pump-probe thermoreflectance techniques. Plasmonic response in waveguides incorporating the adhesion layers will be measured with near-field scanning optical microscopy. A novel in-situ pump-probe measurement of the thermal properties and temperature of the metal-dielectric interface will be developed.
