Enhanced transmission and giant Faraday effect in magnetic metal–dielectric photonic structures

Abstract

Due to their large electrical conductivity, stand-alone metallic films are highly reflective at microwave (MW) frequencies. For this reason, it is nearly impossible to observe Faraday rotation in ferromagnetic metal layers, even in films just tens of nanometres thick. Here, we show using numerical simulations that a stack of cobalt nano-layers interlaced between dielectric layers can become highly transmissive and display a large Faraday rotation in a finite frequency band. A 45° Faraday rotation commonly used in MW isolators can be achieved with ferromagnetic metallic layers as thin as tens of nanometres.