THEORETICAL AND EXPERIMENTAL INVESTIGATION OF THE MAGNETIC-X-RAY DICHROISM OF EARLY 5D IMPURITY ATOMS DISSOLVED IN FERROMAGNETIC FE

Polarization-dependent x-ray absorption is now going to be established as a new probe to study the magnetic and electronic structure of multicomponent systems. New experimental results are presented for early 5d impurity atoms dissolved in ferromagnetic Fe. The observed spectra clearly reflect the antiferromagnetic coupling of the local spin magnetic moment of the early 5d impurity atoms to the magnetization of the Fe host. From the data it is concluded that the change to a ferromagnetic coupling occurs at a higher atomic number in the 5d transition-metal series than deduced earlier from neutron scattering measurements. This conclusion is supported by first-principle calculations for the absorption spectra, which are based on the spin-polarized relativistic Korringa-Kohn-Rostoker-Green function method of band-structure calculation. The theoretical approach presented here, which has recently been applied to calculate the spectra of some late 5d impurities in Fe, results in a very satisfying agreement with experiment and allows a detailed, parameter-free discussion of the observed spectra.