Combined Molecular Dynamics and Micromagnetic Modelling of Nanocomposite Permanent Magnet Particle Arrangement and Properties

Nanocomposite rare-earth permanent magnets composed of exchange-coupled hard magnetic nanoparticles offer a promising route toward high-performance, rare-earth-efficient magnet technologies. In this work, we investigate the structural self-organization and magnetic hysteresis behavior of 40 nm Sm2Co17/Nd2Fe14B hybrid nanoparticles using a combined molecular dynamics (MD) and micromagnetic simulation framework. First, MD simulations are employed to study the Brownian motion and field-induced assembly of the hybrid nanoparticles at two particle concentrations (1 and 5 mg/cm3). In the absence of an external magnetic field, the nanoparticles display dispersed configurations governed by thermal fluctuations and interparticle interactions. Upon application of a high magnetic field (500 mT), the particles align into linear chain-like assemblies, with a more pronounced and rapid aggregation at higher concentration. Subsequently, micromagnetic calculations performed using the OOMMF are used to determine the magnetization reversal behavior of the assemblies. Quasi-static hysteresis loops at low field (40 mT) and room temperature reveal enhanced coercivity and remanence for field-aligned chain structures compared to randomly oriented particle ensembles. Additionally, increasing particle concentration amplifies the field-induced collective response due to stronger dipolar coupling. The combined MD–micromagnetic approach provides insight into structure–property relationships in magnetic nanocomposite systems and highlights the critical role of particle arrangement and concentration in determining magnet performance. These results contribute to the design principles for advanced nanostructured permanent magnets with tunable magnetic anisotropy and energy density.