Large Faraday effect in nanogranular films with a high refractive index matrix

Nanogranular films consisting of a complex of nanometer-sized magnetic granules and a dielectric insulator matrix exhibit a large Faraday rotation. In this study, the dielectric tensor of the nanogranular films with high refractive silicon nitride matrix are measured, and the effect of refractive index of the matrix and magnetic granules on the dielectric tensor is analyzed. Compared with the fluoride (low refractive index) matrix nanogranular films, the Faraday rotation angle is approximately two times higher in the nanogranular FeCo-SiN film, which exhibits a high refractive index effect on the Faraday rotation angle.