A spin selective electron interferometer

Spin polarized low energy electrons with well-defined energy and direction are injected into a spin polarized Cu/Co/Cu(100) quantum well structure. The intensity of the specularly reflected beam oscillates as a function of the Cu thickness, indicating that the quantum well acts as a Fabry-Pérot–type interferometer. The spin resolved intensities are phase shifted, proving spin selectivity of the interferometer. Using this experiment we map the energy dependence of the oscillation period of interlayer exchange coupling and its divergence when the electron energy approaches a Brillouin zone boundary.