The capabilities of the method of using unpolarized neutron off-specular scattering for investigation of magnetic structures in exchange-coupled magnetic multilayers are thoroughly examined. It is demonstrated that strong anomalies in spin-flip selective scattering processes originating from magnetic fluctuations enables a straightforward determination of the coupling angle between the magnetization direction of successive Fe layers in Fe/Cr multilayers. A complete quantitative 2-dimensional data analysis of specular and off-specular scattering has been employed to provide detailed information on the lateral and transverse magnetization arrangement in the multilayer.

The domain structure of an antiferromagnetic superlattice is studied. Synchrotron Mössbauer and polarized neutron reflectometric maps show micrometer-size primary domain formation as the external field decreases from saturation to remanence. A secondary domain state consisting mainly of at least 1 order of magnitude larger domains is created when a small field along the layer magnetizations induces a bulk-spin-flop transition. The domain-size distribution is reproducibly dependent on the magnetic prehistory. The condition for domain coarsening is shown to be the equilibrium of the external field energy with the anisotropy energy.

Hybrid magnetic nanostructures prepared from ultrathin 57Fe layers alternating with thick Cr layers were studied by using polarized neutron reflectometry. It was shown that the sample with Fe layer thickness t=2 Å remains in superparamagnetic state at room temperature. Increasing the Fe-thickness to t=4 Å leads to crossover between superparamagnetic and ferromagnetic spin-glass Fe states and non-zero mean magnetic moment in Fe layers appears.

General equations for spin-flip and non-spin-flip specular reflection and off-specular scattering are analyzed for the case of multidomain states of magnetic multilayers. The results are illustrated by numerical calculations performed for Fe/Cr multilayers using an original software developed on the basis of the supermatrix formalism. This routine allows to calculate the reflectivities and scattering cross sections from the layered structures of any complexity for any directions of the incident polarization vector and directions of the polarization analysis.

A new method is presented for the direct determination of the coupling angle in magnetic exchange multilayers. Strong anomalies in the off-specular neutron spin-flip scattering intensity at critical angles give a new tool, which is tested with Fe/Cr multilayers. In addition, a complete two-dimensional data analysis of specular reflection and off-specular scattering has been employed to verify atomic spin correlation in Fe/Cr multilayers, a typical system showing the GMR effect. (C) 2001 Elsevier Science B.V. All rights reserved.

Off–specular neutron scattering is employed to study islands formation on the surface of deuterated polystyrene–polybutylmethacrylate (PS–PBMA) copolymer film. It is shown, that the intensity distribution measured over a broad range of angles of incidence and scattering is well described by the distorted wave born approximation (DWBA)-based theory valid either in the kinematic regime or in the range of the total reflection. A set of island parameters such as mean lateral size, concentration, as well as those characterizing their internal structure is found.

The distorted wave born approximation (DWBA)-based theory is developed and employed to analyze off-specular neutron scattering from islands on the surface of deuterated polystyrene-polybutylmethacrylate (dPS-PBMA) copolymer film. II is shown that the scattering intensity distribution measured over a broad range of angles of incidence, including the range of total reflection, can be well interpreted within the simple model of random island distribution over the surface. Only a few film and island parameters, such as mean lateral size, concentration, and those characterizing their internal structure are needed to describe a variety of the features observed experimentally. (C) 2000 Elsevier Science B.V. All rights reserved.

The distorted wave Born approximation (DWBA) is applied to evaluate the diffraction pattern of neutrons (or X-rays) from a 2D array of dots deposited onto a dissimilar substrate. With the radiation impinging on the surface at a grazing incidence angle α, the intensities diffracted both in and out the plane of specular reflection are calculated as a function of the periodicity of the array, height and diameter of the dots. The results are presented in the form of diffracted intensity contours in a plane with coordinates α and α′, the latter being the glancing angle of scattering. The optimization of the experimental conditions for polarized neutron experiments on submicron dots is discussed. The feasibility of such measurements is confirmed by a test experiment.

The magnetic field distribution inside thin YBa2Cu3O7 films in the mixed state was studied by polarized neutron reflection. The external field was parallel to the film surface, the thickness of the films was smaller or about equal to the London penetration depth λ. The obtained scattering length density distribution suggests that the magnetic field dependence around a flux-line is changed through the restricted geometry of the thin film. The decay of the magnetic field around a flux-line is not anymore governed by λ but by the thickness of the film.

The effect of oxygen presence in sputtering chamber on magnetization of thin (∼700–800Å) FeCo films was studied by polarized neutron reflectometry. The samples were prepared by magnetron sputtering of the Fe36Co64 alloy onto glass substrates in the presence of oxygen in the sputtering chamber. For a given oxygen content in the sputtering chamber the oxygen concentration in the film decreased with the sputtering rate. The increase in oxygen inside the film was found to decrease its magnetic saturation induction. The exact element depth profiles of the prepared samples was made by Rutherford back scattering (RBS) technique.

The magnetic structure of a [Cr(9Å)/57Fe (68Å)]×12 multilayer on sapphire substrate has been studied with polarized neutron reflectometry. The intensity distribution was measured over a broad range of incident and outgoing angles with spin analysis. The specular and off-specular intensities of the first and second-order Bragg-peaks (determined by the bi-layer thickness) and those at the half-order positions (due to an antiferromagnetic coupling) were measured. Off-specular scattering arranged into sheets running across the antiferromagnetic half-order positions is spread over an appreciable range perpendicular to the specular line. It consists of almost totally spin-flip scattering. Nearly no experimental evidence of the peak at the position of antiferromagnetic superstructure is found in the spin-flip specular channel. The intensity of the diffuse scattering scales with the intensity of the Bragg peaks, which is a function of the external magnetic field. These findings result in a picture of antiferromagnetic domains, rather than in the model of homogeneous magnetized neighbouring layers with a magnetization coupling angle.