Characterization of interlayer coupling in YIG/Py bilayer using polarized neutron reflectometry

The Polarized neutron reflectometry (PNR) was carried out at the Multipurpose Reflectometer (MR) beamline of the Chinese Spallation Neutron Source (CSNS). The substrate size was 10×10 mm2. The room temperature neutron reflectivity curves were recorded at room temperature as the function of momentum transfer Qz = 4𝜋sin𝜃/𝜆, where 𝜆 is the neutron wavelength and 𝜃 is the incident angle between the neutron beam and the film plane. To access a broad momentum transfer range, reflected neutrons were collected at different incident angles. Both R++ and R-- were recorded when neutrons with spins parallel or antiparallel to the applied fields (corresponding to the spin-up and spin-down neutrons), respectively. PNR data were fitted to a model (including the layer thickness and chemical roughness) that was obtained by XRR fitting using the software GenX.