Observation of intercalation of excess oxygen in Bi2Sr2CaCu2O8+y single crystal

TL;DR: The effects arising from intercalation of excess oxygen in Bi-O layer has been observed at room temperature using atomic force microscopy as discussed by the authors, which leads to a change in the local interatomic bond length along the b axis while the periodicity remained invariant along the a axis.

Abstract: Effects arising from the intercalation of excess oxygen in Bi–O layer has been observed at room temperature using atomic force microscopy. The excess oxygen is incorporated by oxygenating the pure sample. The oxygen is trapped between the alternating Bi–O layers along the b direction. This leads to a change in the local interatomic bond length along the b axis, while the periodicity remained invariant along the a axis. In addition, in‐plane atomically resolved structure of single crystal has been imaged at room temperature using AFM. The lattice spacings indicate that the observed structure corresponds to the in‐plane bismuth and oxygen positions. Furthermore, high‐resolution scanning tunneling spectroscopy measurements show that oxygen doping increases the Bi–O layer density of states near the Fermi level giving rise to metallicity, whereas the pure sample reveals a semiconducting energy gap in the tunneling spectrum.