Resonant inelastic X-ray scattering in single-crystal superconducting PrFeAsO

Jarrige, I.; Ishii, Kenji; Fukuda, Tatsuo  ; Yoshida, Masahiro; Ishikado, Motoyuki; Shamoto, Shinichi  ; Hiraoka, Nozomu*; Tsuei, K.-D.*

We have performed a resonant inelastic X-ray scattering (RIXS) measurement at the Fe K edge in a single crystal of the underdoped superconductor compound PrFeAsO (Tc = 42 K). The dependence of the RIXS spectra upon the incident energy E1, measured with the momentum transfer Q = (0 0 6.5) which corresponds to (0,0), is observed to be nearly featureless. In the E1 = 7124 and 7125 eV spectra, we discern a feature centered around 4 eV which undergoes a slight resonant enhancement. The energy of this feature is reminiscent of the metal-ligand charge transfer in the cuprates, therefore we are tempted to ascribe it to the charge transfer between Fe 3d and As 4p.