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Layer-by-layer magnetometry on neutron-polarizing supermirror

Off-specular and grazing incidence small angle neutron scattering with polarization analysis from small magnetic objects on a substrate allow depth-resolved investigation of the lateral magnetic correlations at mesoscopic length scales.

Polarizing supermirrors are commonly used for the polarization of cold neutron beams. They consist of a series of ferromagnetic and non-magnetic layers with a gradient in the layer thicknesses. In the figure, reflectivity and off-specular scattering of polarized neutrons with polarization analysis is shown, recorded during the re-magnetization process of a remnent supermirror.

From these measurements, we can deduce that the bottommost magnetizations flip first along the applied magnetic field, that magnetic fluctuations exist in the layers whose magnetizations have not yet flipped, and that nuclear and magnetic roughnesses coexist. Those affirmations are confirmed by simulations of the measured intensities within the framework of the Distorted Wave Born Approximation (DWBA), whereupon dynamic effects are taken into account.

E. Kentzinger, U. Rücker, B. Toperverg, F. Ott, T. Brückel, PRB 77, 104435 (2008)

Contact: Emmanuel Kentzinger