Study of the grain growth mechanism of CoPt/Cn thin film for magnetic recording media using the Monte Carlo simulation

The effect of carbon addition on the grain growth and ordering kinetics of CoPt film has been studied experimentally by sputter-depositing a monolithic CoPt-20 at.%C film of 24nm. The carbon addition of 20 at.% to CoPt thin film in the form of CoPt (20nm)/Cn (4 nm) (n=1, 4) significantly reduced both the grain growth and ordering kinetics. Reducing the thickness of the carbon layer, i.e. from n=1 to n=4, led to a much finer grain size distribution as well as to a finer grain size. The Monte Carlo simulation study indicated that the decrease of grain growth and ordering kinetics is primarily due to a continuous decrease of the mobility of the order—disorder inter-phase with the progress of the ordering reaction. Reduction of the inter-phase mobility can eventually lead to a stable two phase grain structure inter-locked by low mobility inter-phase and is responsible for the formation of a fine grain size distribution in the CoPt/Cn film with n=4.