  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 6 K, an incommensurate antiferromagnetic
(ICM)structure with a temperature dependent propagation vector (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
a spiral-like magnetic structure with a turn angle of 162 deg between adjacent
Eu planes. In the CM structure, this angle is 180 deg. These results are
consistent with band-structure calculations which indicate a strong sensitivity
of the magnetic configuration on the Eu valence.
