Magnetic structure and UHF conducting properties of composite films (CoFeZr+Al₂O₃) and (CoNbTa+SiO₂)

Abstract

Composite films of A series of compositions [(Co0.45Fe0.45Zr0.10)x + (Al2O3)(1 – x)/5], x = 0.25-0.66 and B series of compositions [(Co0.86Nb0.12Ta0.02)x+(SiO2)(1–x)/3], x=0.14-0.78 were investigated. Images of magnetic micro- and nanostructures of the A, B series composite films were obtained. At small x≤0.3, we observe a chaotic spread of magneto-metallic nanoparticles in a dielectric matrix. In the range 0.30<x<0.55, we observe a mixture of metallic and dielectric microparticles. At large x>0.6, we observe a chaotic scattering of dielectric nanoparticles in a magneto-metallic matrix. We obtained dependences of the specific impedance modulus of composite metal-dielectric films on the current frequency and on the concentration of the metal alloy of A, B series films. The analysis of the spectra showed that films in the frequency range from 0.1 to 3 GHz could exhibit three behaviors of the impedance spectra. For films with x up to the percolation threshold, a capacitive character is observed. The impedance in the field of percolation processes is capacitive, inductive or mixed character. After the percolation threshold, the impedance has an inductive character, and the frequency-dependent character of the magnetic permeability of the films can make a large contribution to the behavior of the spectra.