EuFe2As2: Magnetic Structure and Local Charge Distribution Anisotropies as Seen by Resonant X-ray Scattering

Non-resonant and element specific magnetic X-ray scattering has been used to determine the orientation of Eu and Fe magnetic moments in EuFe₂As₂ iron pnictide. Experiments have been carried out on single crystal samples at the ESRF. Resonant measurements on magnetic reflections at the Eu L₃ absorption edge indicate that the orientation of the Eu moments in the antiferromagnetic phase (T<T _N=19 K) lie parallel to the crystallographic a-axis. In addition, non-resonant magnetic X-ray measurements indicate that the Fe moments are aligned along the same direction in the spin density-wave ordered phase (T<T _S=190 K). The temperature dependence of the integrated intensities suggests that the Fe magnetic sublattice is barely affected by the onset of Eu ordering at T _N. The observation of non-zero resonant intensity on nuclear-forbidden reflections with wavevector corresponding to the Fe magnetic propagation vector at both the Eu L₃ and As K absorption edges may be interpreted as the result of the polarization of the Eu 5d and As 4p electronic bands via hybridization with the Fe 3d states.