Refletividade magnética ressonante de raios X moles de multicamadas FeNi/IrMn/Co: perfil magnético da camada de Co

Abstract

This work is focused on the Soft X-ray Resonant Magnetic Reflectivity (SXRMR) which combines the X-ray absorption, dichroism and reflectivity phenomena emerged from thin film heterostructures and is a selective element technique able to solve the magnetic profile and anisotropy of multilayers within a sub-nanometer resolution (0.4 nm for Fe). Detailed theoretical revision has been done and a program to apply the Kramers-Kronig relations has been developed using the Mathemática language in order to obtain the real and imaginary components of the scattering factors of the elements by using X-ray absorption and dichroism measurements. SXRMRhas been used to solve the magnetic configuration of Si(100)/Ta(3)/NiFe(3)/IrMn(5 e 7)/Co(2)/Ta(1) multilayers (thickness in nm), where NiFe and Co are ferromagnetic materials, while IrMn is an antiferromagnetic spacer. This system has exchange bias effect and one believes that a Néel domain wall is formed in the IrMn generating an exchange spring coupling. In this dissertation, the results for the Co layer are shown, as well as, the correspondent fittings of the SXRMR curves obtained in the RESOXS station at the SEXTANTS beamline of SOLEIL synchrotron/France and their respective asymmetry ratios by using the Dyna Code developed in the Institute Néel/CNRS/France. In order to obtain the scattering factors of the samples, which can diverge from those related to bulk samples, X-ray absorption measurements were performed at DEIMOS beamline also placed at SOLEIL synchrotron, and after that, the Kramers-Kronig relations have been applied. The 2nm Co layer has a homogeneous magnetization (within the error). The SXRMR results indicate that there is no evidence of atomic diffusion or significant hybridization at the Co/ta and IrMn/Co interfaces.