Microstructure and magnetic properties in percolating (Ni–Fe)x(SiO2)1–x granular films

Abstract

We studied composition, structure, microstructure, and magnetic properties of percolating (Ni–Fe)x(SiO2)1−x granular thin films. We found that the magnetic susceptibility increases and the coercivity decreases when increasing x toward xt, the critical metallic volume fraction for the metal-insulator transition, and the susceptibility decreases and the coercivity increases when increasing annealing temperature for x just below xt. Comparison of the microstructure and the magnetic properties suggests that the enhanced magnetic susceptibility for x just below xt is probably associated with the labyrinthine structure of the granular magnetic particles where there is an enhanced surface-to-volume ratio of the magnetic particles.