Fig. 4: Magnetic excitations in Cu₂OSeO₃.

a High-resolution resonant inelastic X-ray scattering (RIXS) spectra measured at an incident energy of 930.9 eV, q = [1.3,0,0] r.l.u. for T = 27, 45, and 100 K, with π polarized light. The zero-energy was determined with reference to a carbon tape placed on the sample. b Fitting analysis of the 45 K RIXS spectrum, using five Gaussian peaks with a fixed width, fixed center position (allowing ±5% variation w.r.t. the values presented in the main text), and free amplitude. Raw data were displayed as open dots. The fitting sum is the solid line. The error bars are defined assuming a Poisson distribution of the single-photon counted events. c Repeating the fitting analysis for all RIXS spectra measured across the Cu L₃ resonance. d Summary of the integrated intensity for each fitting component, as a function of the incident photon energy (dot symbols). The error bars are extracted from the fitting, through the error propagation method. The smoothed lines underneath are a guide for the eyes. The Cu L₃ absorption spectrum is reproduced on top to ease the comparison.