Evolution of the Magnetic Excitations in Electron-Doped La2-1Ce1CuO4

We investigated the high energy spin excitations in electron -doped La2-xCexCuO4, a cuprate superconductor, by resonant inelastic x-ray scattering (RIXS) measurements. Efforts were paid to disentangle the paramagnon signal from non -spin -flip spectral weight mixing in the RIXS spectrum at Q11 = (0.6 pi, 0) and (0.9 pi, 0) along the (1 0) direction. Our results show that, for doping level x from 0.07 to 0.185, the variation of the paramagnon excitation energy is marginal. We discuss the implication of our results in connection with the evolution of the electron correlation strength in this system.