Magnetic ordering in EuRh2As2 studied by x-ray resonant magnetic scattering

Element-specific x-ray resonant magnetic scattering investigations were performed to determine the magnetic structure of Eu in EuRh2As2. In the temperature range from 46 K down to the lowest achievable temperature of 6 K, an incommensurate antiferromagnetic (ICM) structure with a temperature-dependent propagation vector tau approximate to(0 0 0.9) coexists with a commensurate antiferromagnetic (CM) structure. Angular-dependent measurements of the magnetic intensity indicate that the magnetic moments lie in the tetragonal basal plane and are ferromagnetically aligned within the a-b plane for both magnetic structures. The ICM structure is most likely a spiral-like magnetic structure with a turn angle of similar to 162 degrees (0.9 pi) between adjacent Eu planes in the c direction. In the CM structure, this angle is 180 degrees. These results are consistent with band-structure calculations which indicate a strong sensitivity of the magnetic configuration on the Eu valence.