Depth-resolved investigation of the lateral magnetic correlations in a gradient nanocrystalline multilayer

We present an investigation of the structural and magnetic correlations during the remagnetization process of a gradient nanocrystalline multilayer with uniform uniaxial magnetic anisotropy by specular reflectometry and off-specular scattering of polarized neutrons with polarization analysis. The scattering data were analyzed within the distorted wave Born approximation (DWBA) including interfacial roughness correlations and lateral correlations of the spin misalignment. The magnetization reversal proceeds sequentially from the bottommost and thinnest ferromagnetic layers to the topmost and thickest ones. It is quantitatively explained within the random anisotropy model including dominant uniform uniaxial anisotropy. Two types of lateral spin misalignment were deduced, random and not random: The first one in all layers due to the random orientation of the grains, the second one in the layers with nonreversed magnetizations only and due to the applied field acting against the uniaxial anisotropy.