Simulation of energy barrier distributions using real particle parameters and comparison with experimental obtained results

•The path integral method of calculation allows to satisfactorily reproduce the quantitative experimental results.•The simulations of the energy barrier distributions reflect the lognormal distribution of the MNP found in real experiments.•Higher particle volume concentration leads to a broadening of the simulated energy barrier distribution.•At low particle concentration there is only anisotropy energy.•In case of agglomeration the energy barrier distribution broadens.

Distributions of energy barriers in systems of magnetic nanoparticles have been calculated by means of the path integral method and the results have been compared with distributions previously obtained in our experiments by means of the temperature dependent magnetorelaxation method. The path integral method allowed to obtain energies of the interactions of magnetic moments of nanoparticles with axes of their easy magnetisation as well as energies of mutual interactions of magnetic moments. Calculated distributions of energy barriers have been described satisfactorily by curves of the lognormal distribution. We found an agreement between the theory and the experiment at temperatures above approximately 100 K. The influence of the volume concentration of nanoparticles and agglomeration on the energy barrier distribution has been investigated.