Optical properties of BaRuO3: observation of pseudogap formation

We measured temperature-dependent reflectivity spectra of non-perovskite nine layer BaRuO3 single crystal and four layer BaRuO3 epitaxial film. In optical conductivity spectra obtained through Kramers–Kronig transformation, we observed that both materials show pseudogap formations in their metallic states. A clear development of pseudogap as well as a coherent component as a function of temperature is evidently distinguished from other pseudogap systems, such as high Tc cuprates and heavy electron systems. We suggested that these interesting features should be related to the structural characteristics of the layered structures with face-sharing of RuO6 octahedra, which might induce one-dimensional (1D) instability.