Retrieval of the reflection coefficient in neutron specular   reflectometry
  A method is proposed which allows a complete determination of the complex reflection coefficient for any free unknown real potential (i.e., in the case where there is no effective absorption). In this method the unknown layer mounted on top of a known magnetic reference layer in touch with a macroscopic substrate. It lets us to determine the complex reflection coefficient without the effect of the substrate. The method exploits the interference of the spin components of a polarized neutron beam in the presence of a magnetic field. It is based on calculating the polarization of the reflected beam using the elements of transfer matrix and requires the measurement of the polarization in two(one) direction and (two) reflectivity of the reflected beam. A schematic example is presented. 
S.F. Masoudi and A. Pazirandeh