Activity: Talk or presentation › Oral presentation
The material BaBiO3 has been studied extensively, since it is the parent compound of the high- temperature superconductors BaPb(1−x)BixO3 and Ba(1−x)KxBiO3. For thin films, in the ultra-thin limit, metallicity is expected because BaBiO3 is suggested to return to its undistorted cubic phase where the oxygen octahedra breathing mode will be suppressed. Here, the electronic properties of a BaBiO3 thickness series are studied using in-situ scanning tunneling microscopy. We observe a wide-gap to small-gap semiconductor transition as a function of a decreasing BaBiO3 film thickness. Even for an ultra-thin BaBiO3 film, no metallic state is present. The dependence of the band gap size is found to be coinciding with the intensity of the Raman response of the breathing phonon mode as a function of thickness.