Comparison in the electronic structure of YBa2Fe3O8 insulator with YBa2Cu3O7 and SmFeAsO0.8F0.2 superconductors

• The electronic structure of YBa2Fe3O8, YBa2Cu3O7 and SmFeAsO0.8F0.2 were investigated by XPS.
• The core-level and valence-band structures of these systems are different.
• The density of states at Fermi level is related to the superconductivity.

The electronic structure and chemical states of relevant elements of YBa2Fe3O8 are investigated using X-ray photoemission spectroscopy (XPS), compared with those of YBa2Cu3O7 and SmFeAsO0.8F0.2 superconductors. The typical differences and similarities in core-level and valence-band structures of these systems have been detected, strongly suggesting that the superconductivity have the finite density of states around Fermi level. Several features of O1s, Y3d, Ba3d, and Fe2p core lines in XPS spectra are also carefully compared and analyzed.