Influence of Co 3 + spin - state on optical properties of LaCoO 3 and HoCoO 3

Optical properties of the isoelectronic compounds LaCoO3 and HoCoO3 has been experimentally and theoretically investigated. We’ve measured the real ε1(ω) and imaginary ε2(ω) parts of the dielectric function, reflectance R(ω) and optical conductivity at room temperature. The shift of the most pronounced spectral features to the high energy region on 0.3 eV associated with larger distortions due to the smaller rare earth ionic radii in HoCoO3 in comparison with LaCoO3 was observed. Also there was found an enhancement of absorption intensity in the range 1.3-2.3 eV in all kinds of spectra in HoCoO3, which can be attributed basing on the results of LDA+U calculations to the different spin-states of Co ion in these compounds. The shift of the onset of the absorption from less than 0.1 eV in LaCoO3 to 0.7 eV in HoCoO3 and an absorption intensity enhancement in a narrow spectral range 1.2-2.6 eV in HoCoO3 are clearly seen from the calculated convolution of partial densities of states obtained in the LDA+U approach. Such changes are assumed to be induced by the different Co spin-state in these compounds at room temperature. PACS numbers: 78.20.Bh, 71.27.+a, 71.15.Ap Submitted to: J. Phys.: Condens. Matter Influence of Co spin-state on optical properties of LaCoO3 and HoCoO3 2