The charge carrier localization in the cubic perovskite BaOsO3 revealed by an optical study.

We present the optical conductivity spectra for the newly discovered cubic perovskite structure BaOsO3 at various temperatures. The compound exhibits metallic behaviour above 50 K, but becomes non-metallic below 50 K. However, below 550 cm(-1), neither the typical Drude response nor an energy gap is observed in optical conductivity spectra from 300 K to 10 K. A broad peak centred at about 550 cm(-1) is observed in the real part of optical conductivity σ1(ω). The structure could be well reproduced by the localization modified Drude model. The life time of the carrier, deduced from σ1(ω) in terms of the localization modified Drude model, decreases with T varying from 300 K to 100 K, then increases slightly at 10 K. The study indicates that the compound is at the boundary of metal-insulator transition.