921 research outputs found
Retrieval of depth profile of nano scale thin films by one directional polarization analysis in neutron specular reflectometry
Recently it has been shown that the modules and phase of complex reflection
coefficient can be determined by using a magnetic substrate and polarized
neutrons. Several other methods have also been worked out based on measurement
of polarizations of reflected neutrons from magnetic reference layers and
magnetic substrate. However, due to the fact that available reflectometers are
limited in the choice of polarization of reflected beam in the same direction
as the polarization of the incident beam, neither of the methods which are
based on polarization analysis, has been proven to be experimentally practical.
In this paper, we have proposed a new method for determining the phase of
reflection coefficient which is based on two measurements of polarization which
correspond to two magnetic fields with the same magnitudes and different
orientations. The polarization analysis is performed in the same direction as
the polarization of the incident beam and is well suited for available
reflectometers. The problems envisaged in implementation of the method are also
discussed.Comment: 5 pages, 6 figure
Detection of nano scale thin films with polarized neutron reflectometry at the presence of smooth and rough interfaces
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
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