Specular reflection and off-specular scattering of polarized neutrons

The general situation with polarized neutron reflectivity, diffraction on a crystalline structure and off-specular scattering from magnetic inhomogeneities in thin films is thoroughly discussed. It is argued that only a combination of birefringence (spin-dependent refraction) of a neutron wave in the mean magnetic field of the film and spin-flip magnetic diffraction or scattering can lead to the splitting of the outgoing (diffracted or scattered) beam into two beams with different wave vectors and spin states. An effect of interplay between the lateral projection of the coherence length and the in-plane extension of magnetic inhomogeneities (size of domains, roughness correlation length etc.) is outlined. (C) 2001 Elsevier Science B.V. All rights reserved