Magnetic excitations of Sr${}_3$Ir${}_2$O${}_7$ observed by inelastic neutron scattering measurement

In this short note, we report on the first inelastic neutron scattering (INS) study on high-energy magnetic excitations in Sr${}_3$Ir${}_2$O${}_7$. We observed excitations between $\sim$80 meV and $\sim$180 meV. The peak position of the excitations is consistent with the dispersion of a single magnon determined by resonant inelastic X-ray scattering (RIXS) measurement. Thus, our results demonstrate that INS and RIXS observe identical excitations in iridate oxides, as in La${}_2$CuO${}_4$.