Study of the in-plane magnetic structure of neutron polarizing multilayer mirrors

Maruyama, Ryuji   ; Bigault, T.*; Wildes, A. R.*; Dewhurst, C. D.*; Saerbeck, T.*; Honecker, D.*; Yamazaki, Dai  ; Soyama, Kazuhiko  ; Courtois, P.*

Neutron polarizing supermirror needs to display high polarization efficiency at low external fields to meet a variety of research demands. The magnetic properties of these multilayers with a polycrystalline grain size less than the ferromagnetic exchange length can be explained by the random anisotropy model, i.e. competition between the exchange interaction between neighboring spins and the local magnetocrystalline anisotropy. Off-specular scattering and grazing-incidence small-angle scattering measurements with polarized neutrons, each of them covering different length scales, together with the data analysis based on the distorted wave Born approximation, revealed lateral correlation in the fluctuating orientation of the magnetization in the layer on a sub-m length scale. The obtained in-plane magnetic structure was consistent with the random anisotropy model.