Cyrstal field splitting and optical band gap of hexagonal LuFeO$_3$   films
  Hexagonal LuFeO$_3$ films have been studied using x-ray absorption and optical spectroscopy. The crystal splittings of Fe$^{3+}$ are extracted as $E_{e'}-E_{e"}$=0.7 eV and $E_{a_1'}-E_{e'}$=0.9 eV and a 2.0 eV optical band gap is determined assuming a direct gap. First-principles calculations confirm the experiments that the relative energies of crystal field splitting states do follow $E_{a_1'}>E_{e'}>E_{e"}$ with slightly underestimated values and a band gap of 1.35 eV. 
Wenbin Wang, Hongwei Wang, Xiaoying Xu, Leyi Zhu, Lixin He, Elizabeth   Wills, Xuemei Cheng, David J. Keavney, Jian Shen, Xi...
cond-mat.mtrl-sci cond-mat.str-el