Micromagnetic Simulations of Exchange-Coupled Core-Shell Particulate Media

Micromagnetic simulations are used to investigate the reversal of exchange-coupled magnetic core-shell particles and their application to particulate tape recording. With thin soft magnetic shells, the reversal of the core-shell particle remains of Stoner-Wohlfarth type. We find that the thicker the shell or the higher its saturation magnetization, the larger the reduction of the particle switching field, in quantitative agreement with analytical predictions. Recording simulations are also performed for core/shell particulate media. This paper demonstrates that core-shell particles can provide broadband signal-to-noise ratio improvement over conventional single phase nanoparticles, while still satisfying thermal stability and writeability using conventional ring-type writers.