In this article, we present a novel micromagnetic model for L10 ordered FePt grains based on their atomic structure. In this model, each monolayer of Fe atoms is represented by a magnetic moment vector and the entire grain consists of a stack of magnetic moments coupled by magnetostatic and nearest-neighbor exchange fields. The grain model enables simulation of incoherent magnetization switching, especially near the Curie temperature. The model is applied to simulate the heat-assisted recording process in granular L10 FePt thin-film media. One of the unique findings is that grains at transition centers could have a domain wall trapped within, provided sufficient grain height. The existence of these grains, whose magnetic moments could be fractional at transition centers, resulting in significant reduction of medium noise. The noise reduction is effectively equivalent to an increase of the number of grains across the read track width. Enhancing and controlling this mechanism by material engineering could lead to significant increase of area density capability, specifically, increase of track density, without decreasing grain size.

中文翻译：

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L1钪 FePt 晶粒的非相干磁开关


在本文中，我们提出了一种基于 L10 有序 FePt 晶粒原子结构的新型微磁模型。在该模型中，每个单层 Fe 原子都由一个磁矩矢量表示，整个晶粒由一堆由静磁场和最近邻交换场耦合的磁矩组成。晶粒模型能够模拟非相干磁化强度翻转，特别是在居里温度附近。该模型用于模拟粒状 L10 FePt 薄膜介质中的热辅助记录过程。独特的发现之一是，只要有足够的晶粒高度，过渡中心的晶粒可能会有一个畴壁被困在其中。这些颗粒的存在，其磁矩在过渡中心可能是分数，从而导致介质噪声显着降低。噪声的降低实际上相当于读取磁道宽度上颗粒数量的增加。通过材料工程增强和控制这种机制可以显着增加面密度能力，特别是增加轨道密度，而不减小晶粒尺寸。