  By knowing the phase and modules of the reflection coefficient in neutron
reflectometry problems, a unique result for the scattering length density (SLD)
of a thin film can be determined which will lead to the exact determination of
type and thickness of the film. In the past decade, several methods have been
worked out to resolve the phase problem such as dwell time method, reference
layer method and variation of surroundings, among which the reference method
and variation of surroundings by using a magnetic substrate and polarized
neutrons is of the most applicability. All of these methods are based on the
solution of Schrodinger equation for a discontinuous and step-like potential at
each interface. As in real sample there are some smearing and roughness at
boundaries, consideration of smoothness and roughness of interfaces would
affect the final output result. In this paper, we have investigated the effects
of smoothness of interfaces on determination of the phase of reflection as well
as the retrieval process of the SLD, by using a smooth varying function (Eckart
potential). The effects of roughness of interfaces on the same parameters, have
also been investigated by random variation of the interface around it mean
position.

Materials Science