Resonant magnetic soft x-ray diffraction is used to study the magnetic order of the Mn sublattices in multiferroic ${\text{ErMn}}_2{\text{O}}_5$. Data were collected at the $\text{Mn}{L}_{2,3}$ edges as a function of temperature, incident polarization, including the analysis of scattered polarizations for selected azimuths. The energy dependence of the magnetic reflections depends on the azimuthal angle in the commensurate magnetic (CM) ferroelectric (FE) phase, indicating different contributions to the scattering. In the incommensurate magnetic [two-dimensional (2D)-ICM] phase, the two observed reflections ($1/2\pm {\delta }_{\text{x}}$ 0 $1/4+{\delta }_{\text{z}}$) have distinct energy dependences too. Different origins of these differences in spectral shape are discussed. The azimuthal angle dependence at the $L_3$ edge can only be qualitatively described by a generalized magnetic model. The observed discrepancies may indicate the importance of magnetoelectric multipole scattering to these reflections. Reciprocal mesh scans show diffuse scattering along $\mathbf{q}$ and perpendicular to $\mathbf{q}$ as well as along the ($h$ 0 0) direction in the CM phase. Diffuse scattering is also observed along ($h$ 0 0) in the one-dimensional-ICM phase. At higher temperatures, in the 2D-ICM phase, the diffuse magnetic scattering is almost isotropic.

• Received 20 January 2010

DOI:https://doi.org/10.1103/PhysRevB.81.144401