The Study of the Influence of Matrix, Size, Rotation Angle, and Magnetic Field on the Isothermal Entropy, and the Néel Phase Transition Temperature of Fe2O3 Nanocomposite Thin Films by the Monte-Carlo Simulation Method

In this paper, the study of the influence of the matrix structure (mxm) of thin-film, rotation angle (α), magnetic field (B), and size (D) of Fe2O3 nanoparticle on the magnetic characteristic quantities such as the magnetization oriented z-direction (MzE), z-axis magnetization (Mz), total magnetization (Mtot), and total entropy (Stot) of Fe2O3 nanocomposites by Monte-Carlo (MC) simulation method are studied. The applied MC Metropolis code achieves stability very quickly, so that after 30 Monte Carlo steps (MCs), the change of obtained results is negligible, but for certainty, 84 MCs have been performed. The obtained results show that when the mxm and α increase, the magnetic phase transition appears with a very small increase in temperature Néel (TNtot). When B and D increase, TNtot increases very strongly. The results also show that in Fe2O3 thin films, TNtot is always smaller than with Fe2O3 nano and Fe2O3 bulk. When the nanoparticle size is increased to nearly 12 nm, then TNtot = T = 300 K, and between TNtot and D, there is a linear relationship: TNtot = −440.6 + 83D. This is a very useful result that can be applied in magnetic devices and in biomedical applications.