Spin-orientation dependence in neutron reflection from a single magnetic film

We demonstrate that the magnetic state of a thin magnetic film can be probed using polarized neutron reflection even when the magnetization in the film plane is at 90^∘{} to the polarization direction of the incident neutron beam. For this special case, no magnetic interaction is expected classically, thus the effect is entirely quantum mechanical in origin. We show both theoretically and experimentally that it arises from the independent interaction of each spin component with the magnetization in the film. We demonstrate this effect for a single Co/GaAs(001) film and discuss its application to magnetic measurements using an unpolarized neutron beam.