  Due to their large electric conductivity, stand-alone metallic films are
highly reflective at microwave frequencies. For this reason, it is nearly
impossible to observe Faraday rotation in ferromagnetic metal layers, even in
films just tens of nanometers 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-degree Faraday rotation can be achieved with metallic
ferromagnetic layers as thin as tens of nanometers.
