Towards understanding of magnetization reversal in Nd-Fe-B nanocomposites: analysis by high-throughput micromagnetic simulations

We demonstrate how micromagnetic simulations can be employed in order to characterize and
analyze the magnetic microstructure of nanocomposites. For the example of nanocrystalline
Nd-Fe-B, which is a potential material for future permanent-magnet applications, we have
compared three different models for the micromagnetic analysis of this material class: (i) a
description of the nanocomposite microstructure in terms of Stoner-Wohlfarth particles with
and without the magnetodipolar interaction; (ii) a model based on the core-shell representation
of the nanograins; (iii) the latter model including a contribution of superparamagnetic clusters.
The relevant parameter spaces have been systematically scanned with the aim to establish
which micromagnetic approach can most adequately describe experimental data for this
material. According to our results, only the last, most sophisticated model is able to provide
an excellent agreement with the measured hysteresis loop. The presented methodology is
generally applicable to multiphase magnetic nanocomposites and it highligths the complex
interrelationship between the microstructure, magnetic interactions, and the macroscopic
magnetic properties.