Manipulating ballistic electrons by refraction at an interface between isotropic and anisotropic media

Electron beams can be steered or collimated after refraction at an interface between an isotropic medium and an isotropic one. In this situation the refraction can be negative or positive as a function of the incidence angle. The materials´ parameters influence the steering angle, whereas the energy of the ballistic electrons determines the degree of collimation.