Strong spin-dependent absorption at theL 2,-edges of 5d-impurities in iron

Large spin-dependent absorption effects have been observed with circularly polarized photons of energies between 10.8 keV and 13.8 keV at the $L_{2,3}$-edges of Os, Ir, Pt, and Au impurities (3 at.%) in iron. The largest value of the spin-dependent absorption coefficient (µc/µo∼+0.22) is found at the Pt L$_2$ -edge. From the energy dependence of the spin-dependent absorption at theL2- andL3-edges the spin-density profiles of the $d_{3/2}$-and $d_{5/2}$-projected states populated in the absorption process are derived. The d$_{5/2}$-spin densities deduced from the L$_3$ spin-dependent absorption spectra agree well with spin-polarized band-structure calculations for the ferromagnetic ground state. A comparison of thed3/2- andd5/2-spin densities shows a strong contribution of the spin-orbit effects to the exchange splitting in Os, whereas only small spin-orbit effects are indicated for Ir, Pt and Au impurities