Structural origin of resonant diffraction in RuO2

We report Ru L3-edge resonant X-ray diffraction studies on single-crystal and (001)-oriented epitaxial films of RuO2. We investigate the distinct Q = (100) and (001) Bragg-forbidden reflections as a function of incident energy, azimuthal angle, and temperature. The results show that the observed resonant diffraction in RuO2 is fully consistent with a resonant charge anisotropy signal of structural origin permitted by the parent (nonmagnetic) rutile P42/mnm space group. These results significantly constrain the magnetic contribution to the resonant diffraction signal and indicate the unlikely existence of k = 0 antiferromagnetic order in RuO2.