Polarizing supermirrors

Sputtering techniques allow, by means of alloying and reactive processes, to produce artificial multilayers on a nano-meter scale with non-stochiometric compositions. Hence it is possible to adjust the index of refraction of individual layers. This property is particularly important for the fabrication of polarizing mirrors. In addition, composite layers are usually smoother and less prone to interdiffusion, i.e., more-stable with temperature. For example, Fe₅₀Co₄₈V₂/TiN_x supermirrors survive temperatures as high as T ≃ 230°C. Moreover, by using anisotropic sputtering conditions, remanent mirrors can be produced with the magnetization direction pointing along any desired direction, thus allowing the fabrication of spin selectors for applications in zero field environments.