热辅助磁存储技术是一种提高磁盘存储面密度到1 Tb·in?2的方法,在数据写入过程中的激光局部加热会使磁盘非晶碳薄膜氧化.本文采用ReaxFF反应力场分子动力学方法,建立硅掺杂非晶碳(a-C:Si)薄膜在激光诱导氧化的模型,从原子尺度分析a-C:Si薄膜的结构变化、氧化过程,确定了氧化机理以及激光加热次数对氧化的影响规律.a-C:Si薄膜的氧化发生在加热阶段和初始降温阶段,在加热过程中a-C:Si薄膜的体积扩张和降温过程中原子应变引起碳原子团簇,均使薄膜中sp2碳含量增加.随着加热次数的增加,表面未饱和原子数量减少和氧原子低扩散率使薄膜氧化速率逐渐降低.此外,非晶薄膜的表面缺陷使分子氧成为氧化剂,表面原子剪切应变使Si―O―O―Si链中O―O键断裂,重构氧化表面,进而促进a-C:Si薄膜的氧化.%Heat-assisted magnetic recording (HAMR) is one of the promising ways to extend the magnetic recording area density to 1 Tb·in?2 in hard disk drives (HDDs). High temperature induced by laser heating can cause carbon overcoat (COC) oxidation. Reactive molecular dynamics (MD) simulations are performed to investigate the oxidation process of silicon-doped amorphous carbon (a-C:Si) films for HAMR application. The atomic details of the structure evolution and oxidation process are investigated, and, the oxidation mechanism of the a-C:Si film is clarified. The effect of the duration of laser irradiation on the oxidation of the a-C:Si film is investigated. The oxidation occurs during heating and the beginning of cooling process. Both volume expansion during heating process and cluster of carbon atoms during cooling process increase the rate ofsp2 carbon. Because of the decrease in the amount of unsaturated silicon atoms and low diffusion coefficient of atomic oxygen, the oxidation rate of the a-C:Si film decreases with laser irradiation cycles. The molecular oxygen is the oxidant due to surface defect of a-C:Si film. The atomic strains break the O―O bonds in Si―O―O―Si linkages and rearrange the surface oxide layers, and process the oxidation of the a-C:Si film.
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