Multi-level magnetic recording is a new concept for increasing the data storage capacity of hard disk drives. However, its implementation has been limited by a lack of suitable media capable of storing information at multiple levels. Herein, we overcome this problem by developing dual FePt-C nanogranular films separated by a Ru-C breaking layer with a cubic crystal structure. The FePt grains in the bottom and top layers of the developed media exhibited different effective magnetocrystalline anisotropies and Curie temperatures. The former is realized by different degrees of ordering in the L1-FePt grains, whereas the latter was attributed to the diffusion of Ru, thereby enabling separate magnetic recording on each layer under different magnetic fields and temperatures. Furthermore, magnetic measurements and heat-assisted magnetic recording simulations showed that these media enabled 3-level recording and could potentially be extended to 4-level recording, as the ↑↓ and ↓↑ states exhibited non-zero magnetization.

中文翻译：

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用于多级热辅助磁记录的双层FePt-C颗粒介质

多级磁记录是增加硬盘驱动器数据存储容量的新概念。然而，由于缺乏能够存储多级信息的合适介质，其实施受到限制。在这里，我们通过开发由具有立方晶体结构的 Ru-C 断裂层分隔的双 FePt-C 纳米颗粒薄膜来克服这个问题。所开发介质的底层和顶层中的 FePt 晶粒表现出不同的有效磁晶各向异性和居里温度。前者是通过L1-FePt晶粒中不同程度的有序化来实现的，而后者则归因于Ru的扩散，从而能够在不同的磁场和温度下在每一层上进行单独的磁记录。此外，磁测量和热辅助磁记录模拟表明，这些介质能够实现 3 级记录，并且有可能扩展到 4 级记录，因为 ↑↓ 和 ↓↑ 状态表现出非零磁化。