Seminars Archive

X-ray magnetic dichroism shows every atom has its moments

Abstract
Conventional magnetism has largely ignored the anisotropy of the spin and orbital magnetic moments and so far not much is known about the factors which influence the preferred magnetization of thin films, multilayers and interfaces. The preferred orientation of the magnetization is determined by the magnetocrystalline anisotropy energy (MAE). In thin films and multilayers the MAE is usually strongly increased from the bulk due to the symmetry breaking. It is shown how the newly developed experimental tool of Transverse X-ray Magnetic Circular X-ray Dichroism (XMCD) can be used to determine the easy axis of magnetization for each constituent of a composite magnetic system. It is argued that X-ray Magnetic Linear Dichroism (XMLD) might be able to conduct magneticians to the holy grail of the element-specific magnetic anisotropy. For itinerant 3d transition metal systems the MAE is directly related to the anisotropic part of the spin-orbit interaction which can be obtained by applying the sum rule for linear dichroism. This appliance might also be practical to dissect the MAE into the different contributions of the spin-orbit related anisotropy and the shape anisotropy due to dipole-dipole interactions.