Fig. 4.

Summary of the best fit parameters obtained for the dispersion of the magnon modes M1 (blue squares) and M2 (red spheres) along $[h,0]$ and $[h,h]$ at the bulk resonance energy of 931 eV and the interface resonance energy of $930.5$ eV, respectively. Calculation of the error bars is discussed in Section S2.3 (40).