Using neutron reflectometry to understand enhanced dynamic linewidth in a magnetic trilayer device (continuation)

We have studied magnetic damping of CoFe/Ag/CoFe multilayer films using ferromagnetic resonance spectroscopy. There is an anomalous linewidth enhancement, which oscillates with a period of around 1 nm as the Ag thickness is increased. Theoretical studies predict dynamic exchange coupling across non-magnetic spacers to affect the resonance linewidth; the enhanced damping in CoFe/Ag/CoFe may rely on the interlayer coupling which may be ferromagnetic or antiferromagnetic due to the well-known Ruderman-Kittel-Kasuya-Yosida (RKKY) mechanism. Our previous experiment found uniaxial magnetic anisotropy (UMA) may also play a role. The aim of this experiment is to determine the UMA and RKKY coupling strengths from depth-resolved vector magnetometry using polarised neutron reflectometry with polarisation analysis, to clarify interpretation of the anomalous linewidth behaviour in CoFe/Ag/CoFe.