We employ an atomistic model using a nearest-neighbor Heisenberg Hamiltonian exchange to study computationally the dependence of the Curie temperature of $L{1}_0$-FePt on finite-size and surface effects in heat-assisted magnetic recording (HAMR) media. We demonstrate the existence of a size threshold at 3.5 nm below which the impact of finite-size effects starts to permeate into the center of the grains and contributes to the reduction of the Curie temperature. We find a correlation between the Curie temperature and the percentage of atomistic bonds lost on the surface as a function of grain size, which can be extended to apply to not only $L{1}_0$-FePt but also generic magnetic systems of any crystal structure. In a recording medium, the inevitable grain size dispersion leads to an irreducible contribution to the dispersion of the Curie temperature. Therefore, our paper gives insight into finite-size effects, which have been predicted to be a serious limitation of HAMR.

中文翻译：

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有限尺寸效应对L10−FePt居里温度的影响

我们采用使用最近邻海森堡哈密顿交换的原子模型来计算地研究居里温度的依赖性$\mathrm{大号}{1}_0$-FePt 对热辅助磁记录 (HAMR) 介质中有限尺寸和表面效应的影响。我们证明了在 3.5 nm 处存在尺寸阈值，在该阈值以下，有限尺寸效应的影响开始渗透到晶粒中心并有助于降低居里温度。我们发现居里温度与表面上失去的原子键百分比之间的相关性是晶粒尺寸的函数，它可以扩展到不仅适用于$\mathrm{大号}{1}_0$-FePt 以及任何晶体结构的通用磁性系统。在记录介质中，不可避免的粒度分散导致对居里温度分散的不可减少的贡献。因此，我们的论文深入了解了有限尺寸效应，这已被预测为 HAMR 的严重限制。