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A structural simulation strategy was developed for characterizing the thin films of ferromagnetic - ferroelectric nanocomposites consisting of a spinel and a perovskite. The (1-y) Ni0.5Zn0.5Fe2O4 - y BaTiO3 magnetoelectric ceramic, with (1-y) = 0.5 - 0.9 obtained by ferrite grains embedding into the BaTiO3 matrix has found multiple applications for magnetoelectric sensors, four-state memories, anti-electro-magnetic interference (EMI) devices, etc. The tunability of the electromagnetic properties, considered until now as a matter of chemistry, strictly depending on the synthesizing process of the nanocomposite, can be reached by the 3D simulation methods, which reproduce the structure and simulate the interactions between constituents and with external fields.  The thin film samples were simulated in the field of a horn antenna (4 ÷ 18 GHz), above the ferromagnetic resonance of the pure ferrite. The effective permittivity, respectively permeability were determined and their evolutions with different internal and external parameters (relative volume fractions, substitution ion radii in the ferrite, polarizing fields) were linked on the intrinsic characteristics of the constituent phases. The obtained surface plots indicates us the sets of optimal control parameters which have to be correlated in practice in order to obtain the desired value of an effective parameter, in a considered frequency subdomain. It appears that the system behaves optimal at a frequency around 8.9 GHz, where the values of the correlated control parameters is convenient for applications at microwave devices. A ferromagnetic - ferroelectric system tunability ranging from 13 to 37% was achieved, depending upon each structure characteristics.

The GHz range is a domain not enough exploited for application in the case of the materials like the CdCr2S4 multiferroic which possesses all four properties of colossal magnetoresistance, electroresistance, is colossal magnetocapacitive and electrocapacitive. The 3D simulation by structural description of such a material represents a real challenge of the descriptive simulational science, due to the complexity of the internal phenomena and interactions which occur here. Dielectric and magnetic properties were reported up to 3 GHz by measurements (Hemberger et al. and so on), while our simulation method is coming to extrapolate the results up to 18 GHz for applications in spintronics and microelectronics. The geometrically frustrated thiospinel system, included in the Heisenberg 3D ferromagnets class, was described with help of the HFSS 13.0 program. An algorithm based on physical consideration was used for the material samples simulated inside a rectangular waveguide, in order to determine their complex electromagnetic parameters (electric permittivity and magnetic permeability). Maxima were found on the real permittivity / permeability graph and by overlapping of the graphs, distinctive resonances were separated. Resonances were linked on the internal structure and the exciting field interaction with the material samples, considering that each mechanism of interaction is dominated by the characteristics of the ferroic propriety involved. A structural resonance map for the microwave range up to 18 GHz was represented. The material presenting all four ferroic properties has resonances specific for each property, but also cumulative resonances, of various magnitude, which can be described only by considering two or more ferroic properties characterizing the same material state.