Abstract
The atomically resolved local barrier height (LBH) of a Bi2Sr2CaCu2O8+δ (Bi2212) superconducting single crystal is investigated by using scanning tunneling microscopy/spectroscopy (STM/STS). The LBH distribution is found to be strongly related with the well-known supermodulation structure of the Bi2212 surface with a period of ∼2.7 nm. In particular, the magnitude of the LBH is anticorrelated to the Bi–Bi atomic distance that is affected by supermodulation. A comparison with simultaneously obtained conductance spectra shows that there is a small correlation between the spatial modulation of the gap amplitude (Δ) and the LBH, this indicates that the measured Δ is slightly affected by the topmost BiO surface, but dominantly reflects information on the inner CuO2 layer, which is responsible for the superconductivity.
