Multiscale Model Approach for Magnetization Dynamics Simulations

TL;DR

This paper introduces a multiscale simulation approach for magnetization dynamics that combines micromagnetic and atomistic models, enabling efficient and accurate analysis of large ferromagnetic systems with localized nanoscopic features.

Contribution

The authors developed a multiscale simulation framework that adaptively integrates micromagnetic and atomistic models within a single environment, improving simulation efficiency and accuracy.

Findings

Spin wave transmission is fully transparent across model interfaces below a certain frequency.

Multiscale simulation results agree well with analytical theory for systems with Dzyaloshinskii-Moriya interaction.

The approach enables large-scale simulations with localized nanoscopic detail.

Abstract

Simulations of magnetization dynamics in a multiscale environment enable rapid evaluation of the Landau-Lifshitz-Gilbert equation in a mesoscopic sample with nanoscopic accuracy in areas where such accuracy is required. We have developed a multiscale magnetization dynamics simulation approach that can be applied to large systems with spin structures that vary locally on small length scales. To implement this, the conventional micromagnetic simulation framework has been expanded to include a multiscale solving routine. The software selectively simulates different regions of a ferromagnetic sample according to the spin structures located within in order to employ a suitable discretization and use either a micromagnetic or an atomistic model. To demonstrate the validity of the multiscale approach, we simulate the spin wave transmission across the regions simulated with the two different models and different discretizations. We find that the interface between the regions is fully transparent for spin waves with frequency lower than a certain threshold set by the coarse scale micromagnetic model with no noticeable attenuation due to the interface between the models. As a comparison to exact analytical theory, we show that in a system with Dzyaloshinskii-Moriya interaction leading to spin spiral, the simulated multiscale result is in good quantitative agreement with the analytical calculation.