Fractal perspective of RKKY exchange interactions in L10 FePt

This paper introduces an approach to approximating exchange interactions in FePt, characterizing their effect on the Curie temperature and magnetic anisotropy, properties crucial for heat-assisted magnetic recording. The proposed model employs the Ruderman-Kittel-Kasuya-Yosida (RKKY) function, offering a different perspective on magnetization processes within finite FePt grains. The RKKY function is derived as a specific instance of a fractal curve, such as the Jacobi elliptical function. The study showcases a holographic implementation of these exchange interactions, translatable into an atomistic spin dynamics model, yielding valid outcomes for finite-size scaling laws. The primary goal is to formulate an approximate spin Hamiltonian with fewer neighbors, enhancing the efficiency of simulations for the FePt which is a candidate for heat-assisted magnetic recording media. Additionally, the research delves into how the number of interactions per bond impacts magnetization evolution across different temperatures and system sizes. Our findings suggest that this model is more computationally efficient for Monte Carlo simulations than the comprehensive density-functional-theory-based spin Hamiltonian proposed by Mryasov et al.