Low Energy Electronic Excitations in the Layered Cuprates Studied by CopperL3Resonant Inelastic X-Ray Scattering

We have measured the resonant inelastic x-ray scattering (RIXS) spectra at the Cu $L_3$ edge in a variety of cuprates. Exploiting a considerably improved energy resolution (0.8 eV) we recorded significant dependencies on the sample composition and orientation, on the scattering geometry, and on the incident photon polarization. The RIXS final states correspond to two families of electronic excitations, having local ($dd$ excitations) and nonlocal (charge-transfer) character. The $dd$ energy splitting can be estimated with a simple crystal field model. The RIXS at the $L_3$ edge demonstrates here a great potential, thanks to the resonance strength and to the large $2p$ spin-orbit splitting.