Small-angle neutron spin-flip scattering in ferromagnetic films

This paper reports on the results of reflectometric measurements of anisotropic (Co₆₇Fe₃₁V₂) and almost isotropic (Fe) films prepared by magnetron sputtering. Nonspecular reflections and the corresponding peaks of the intensities of refracted neutrons have been observed for the alloy samples in magnetic fields H ≤ 7 Oe applied in the film plane along the easy magnetization axis. For iron films, angular splitting of the reflected neutron beam becomes observable only at H > 100 Oe and increases with an increase in the magnetic field. A general scheme has been proposed for this small-angle scattering with allowance made for different variants of changes in the Zeeman energy of neutrons. This scheme has allowed us to identify the magnetic structures of Co-Fe films. The magnetization of 0.15-μm-thick films with uniaxial and unidirectional textures leads to the formation of unidirectional textures characterized by different intensity distributions, for which the qualitative differences are retained with an increase in the magnetic field from 7 to 800 Oe. It has been revealed that, for 2.5-μm-thick films with the initial unidirectional texture, the oppositely magnetized states are nonequivalent.