Crystal field splitting and optical bandgap of hexagonal LuFeO3 films

Hexagonal LuFeO3 films have been studied using x-ray absorption and optical spectroscopy. The crystal splitting of Fe3+ is extracted as E-e' - E-e '' = 0.7 eV and E-a1' - E-e' = 0.9 eV, and a 2.0 eV optical bandgap is determined assuming a direct gap. First-principles calculations confirm the experiments that the relative energies of crystal field splitting states do follow E-a1' > E-e' > E-e '' with slightly underestimated values and a bandgap of 1.35 eV. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4771601]