Optical properties and electronic structure of multiferroic hexagonal   orthoferrites RFeO3 (R=Ho, Er, Lu)
  We report on optical studies of the thin films of multiferroic hexagonal (P.G. 6mm) rare-earth orthoferrites RFeO3 (R=Ho, Er, Lu) grown epitaxially on a (111)-surface of ZrO2(Y2O3) substrate. The optical absorption study in the range of 0.6-5.6 eV shows that the films are transparent below 1.9 eV; above this energy four broad intense absorption bands are distinguished. The absorption spectra are analyzed taking into account the unusual fivefold coordination of the Fe(3+) ion. Temperature dependence of the optical absorption at 4.9 eV shows anomaly at 124 K, which we attribute to magnetic ordering of iron sublattices. 
V. V. Pavlov, A. R. Akbashev, A. M. Kalashnikova, V. A. Rusakov, A. R.   Kaul, M. Bayer, R. V. Pisarev
cond-mat.mtrl-sci cond-mat.other