Origin of incommensurate satellite reflections on TbMnO3 by resonant x-ray scattering

We have performed a deep spectroscopic study of incommensurate satellite reflections (h, k, l) ± (0,0.278, 0) on a TbMnO3 single crystal in order to shed light on its physical origin. Resonant x-ray scattering experiments at the Mn K-edge and Tb L3-edge have been performed at different temperatures and azimuthal angles, analyzing the outgoing light polarization. Our experimental results agree with a magnetic origin for A and C-type reflections, while F and G-type have the hallmarks of anisotropic tensor susceptibility (ATS) reflections, so that they come purely from the structural modulation.