GOALI/Collaborative Research: Effect of Stress and Heat on Magnetic Properties of Thin Films

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The properties of magnetic materials are affected by stress and heat. When a ferromagnetic material experiences surface contact, it can degrade or change its original magnetic properties. The magnetic stability decreases as the size of the microscopic magnetic domain in the material decreases. In order to improve the performance of ferromagnetic devices, the physical size of magnetic domains needs to be reduced. This Grant Opportunity for Academic Liaison with Industry (GOALI) Program collaborative research award supports fundamental research to investigate the scientific mechanism of magnetic degradation for ferromagnetic thin films under stress, heat, and friction. With the collaboration between universities and industrial partner, the fundamental research activities will be brought into actual product, i.e., magnetic recording media in a hard disk drive (HDD), to achieve more stable and reliable design. The outcomes from this multi-disciplinary and collaborative research will not only provide immediate solutions to improve energy efficiency, accuracy and reliability of magneto-mechanical applications (e.g., magnetic storage devices, magnetic sensors and actuators, magnetic MEMS/NEMS resonator, etc.) but also deliver key design rules for the next-generation ferromagnetic devices. The coupled effects of micro-stress and thermal agitation by adiabatic/frictional heat generation will be systematically and quantitatively examined with respect to magnetic design parameters of materials such as magnetic domain size and magnetic anisotropy energy density. First, in theoretical modeling, the theories of contact mechanics and heat transfer will be incorporated into magnetic properties, where the micro-stress tensor and spatial temperature distribution change magnetic field and magnetization. Second, in computational simulation, atomic level disorders obtained from the ab-initio calculation will be extended to the macroscopic magnetization process, where Monte Carlo simulation will be applied to minimize the system energy. Lastly, the scientific findings from the theoretical and computational simulations will be verified through dynamic surface contact experiment and instrumental material characterization.