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The paper refers to Monte Carlo (MC) magnetic simulations and finite element scaling rules, allowing the simulation of magnetic mesoscopic systems. The scaling rules consist of a redefinition of the system Hamiltonian as a function of a scaling factor, including spin values and exchange integral parameters attributed to system nodes. This approach leads to a disturbance of the thermodynamic balance expressed by acceptance probability in the Metropolis steps. This paper aims to explain the effect and solve the problem.

The change of the acceptance probability is derived from energy change and the scaling roles. As a test, a set of thermomagnetic curves was simulated in the temperature ranges related to ferro-paramagnetic transitions for the systems with different enlargement factors.

The presented approach allows the simulation of thermomagnetic curves of large magnetic systems using the MC Metropolis algorithm modified by the scaling rules.

The presented approach allows the simulation of thermomagnetic curves of large magnetic systems, using the MC Metropolis algorithm modified by the scaling rules.

The presentation refers to simulations of magnetization processes of the spring-exchange magnetic composites containing magnetically soft and ultra-high coercive phases. In particular, the aim of this study is to investigate the possibility of reducing expensive rare earth (RE) in the so-called neodymium magnets and improving their efficiency.

In order to model hysteresis loops, a special disorder-based Monte Carlo procedure, suitable for irregular geometry of the composites, was applied. The chosen system parameters were defined in order to model Nd2Fe14B/Fe composites.

The results suggest potential for optimizing hard magnetic composites. Magnetization curve parameters are sensitive to grain coupling and easy magnetization axis ordering. Strong coupling for a single-phase hysteresis loop is unachievable for grains above a certain size, i.e. found to be a few hundred nanometers. Considering these factors and their interdependencies, it’s possible to enhance the |BH|max parameter or reduce the RE content.

The research was carried out using computer simulations, which by their nature are only approximations of physical processes. The next stage of research is to produce the described composites and test their actual properties.

The research enhances permanent magnets, boosting efficiency in technologies like wind turbines and electric motors, indirectly benefiting the environment. It also reduces RE elements in magnets for environmental, economic and political gains.

The unique approach is to consider the random orientation of the magnetic anisotropy of the hard magnetic grains, which is close to real powder composites. The results provide valuable guidance for the production process of permanent magnets.