Polarization-resolved Cu L3 -edge resonant inelastic x-ray scattering of orbital and spin excitations in NdBa2Cu3O7−δ

RIXS spectra are populated by features due to orbital, charge, and spin excitations. The correct assignment is usually based on their energy and on the incident polarization dependence. In addition, several ambiguities can be lifted by measuring the scattered photon polarization. Here, a polarization-resolved Cu ${L}_{3}$ RIXS systematic study of NdBa${}_{2}$Cu${}_{3}$O${}_{7\ensuremath{-}\ensuremath{\delta}}$ as a function of doping and momentum is presented. With the help of single-ion model calculations, a definitive assessment of orbital excitations is made, even in the doped materials where the intrinsic broadening smears spectral features.