Influence of electronic correlations on orbital polarizations in the   parent and doped iron pnictides
  Orbital polarization and electronic correlation are two essential aspects in understanding the normal state and superconducting properties of multiorbital FeAs-based superconductors. In this Letter, we present a systematical study on the orbital polarization of iron pnictides from weak to strong Coulomb correlations within the KRSB approach. The magnetic phase diagram of the two-orbital model for LaFeAsO clearly shows that the striped antiferromagnetic metallic phase with considerable orbital polarization exists over a wide doping range. The reversal of the orbital polarization occurs in the intermediate correlation regime.A small crystal field splitting enhances the orbital density wave order. 
Ya-Min Quan, Liang-Jian Zou, Da-Yong Liu and Hai-Qing Lin
cond-mat.supr-con cond-mat.str-el