Electron spin interferometry

In a simple experiment, we monitor interference effects for low energy electrons in thin magnetic Co-films as well as in a spin quantum resonator structure consisting of a Cu-film of variable thickness sandwiched between vacuum and a magnetic Co-film. In the case of the Co-film the incident electrons are unpolarized and we observe oscillations with a period of one monolayer as a function of Co-thickness when we measure the intensity of the reflected electron beam. We attribute these oscillations to the changing morphology of the Co film as a function of thickness. In the case of the sandwich structure, spin polarized electrons are injected into the resonator from the vacuum side. The Co-film provides a spin dependent reflector. Varying the resonator thickness results in periodic switching of the spin state of the specularly reflected electrons. We apply spin interferometry to study oscillatory interlayer exchange coupling and find a divergence of the coupling period predicted by theory.