%0 Journal Article
%T Resonant inelastic x-ray scattering study of electronic excitations in insulating K$_{0.83}$Fe$_{1.53}$Se$_2$
%A H. Gretarsson
%A T. Nomura
%A I. Jarrige
%A A. Lupascu
%A M. H. Upton
%A Jungho Kim
%A D. Casa
%A T. Gog
%A R. H. Yuan
%A Z. G. Chen
%A N. -L. Wang
%A Young-June Kim
%J Physics
%D 2014
%I arXiv
%X We report an Fe $K$-edge resonant inelastic X-ray scattering (RIXS) study of K$_{0.83}$Fe$_{1.53}$Se$_2$. This material is an insulator, unlike many parent compounds of iron-based superconductors. We found a sharp excitation around 1 eV, which is resonantly enhanced when the incident photon energy is tuned near the pre-edge region of the absorption spectrum. The spectral weight and line shape of this excitation exhibit clear momentum dependence. In addition, we observe momentum-independent broad interband transitions at higher excitation energy of 3-7 eV. Calculations based on a 70 band $dp$ orbital model, using a moderate $U_{\rm eff}\approx 2.5$ eV, indicate that the $\sim$1 eV feature originates from the correlated Fe 3$d$ electrons, with a dominant $d_{xz}$ and $d_{yz}$ orbital character. We find that a moderate $U_{\rm eff}$ yields a satisfying agreement with the experimental spectra, suggesting that the electron correlations in the insulating and metallic iron based superconductors are comparable.
%U http://arxiv.org/abs/1412.6429v2