Controlled Properties of the Thin Films of Ni_0.5Zn_0.5Fe₂O₄- BaTiO₃ Ferrite-Ferroelectric Nanocomposites - Simulational Study

Abstract

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.