Structural and stoichiometric modifications in ultrathin epitaxial BaBiO 3 films
Abstract
BaBiO3 (BBO) is well known as the parent material for the high-Tc superconducting compounds Ba1 -xKxBiO3 and BaPb1 -xBixO3 . In its pristine state, BBO is a charge-ordered (CO) insulator, resulting from a static breathing distortion of the BiO6 octahedra with alternating long and short bond lengths. Recently, it has been reported that the CO state is suppressed for BBO films grown on SrTiO3 (STO) below a thickness of approximately 4 nm, possibly resulting in a metallic phase. While we do confirm structural modifications in our BBO/Nb:STO samples in this thickness range by Raman spectroscopy and electron diffraction, in situ photoemission evidences that these changes are accompanied by a Bi deficit and that the films remain insulating. We hence conclude that, in line with previous findings for the BBO/STO interface, the thickness-controlled suppression of the CO state is not purely driven by the two-dimensional confinement but rather originates from modifications of the composition and structure inherent to the epitaxial growth of BBO on SrTiO3(001).
- Publication:
-
Physical Review B
- Pub Date:
- June 2019
- DOI:
- 10.1103/PhysRevB.99.245308
- Bibcode:
- 2019PhRvB..99x5308Z