Imaging and identification of atomic planes of cleaved Bi₂Sr₂CaCu₂O_8+δ by high resolution scanning tunneling microscopy

Imaging of the surface of a cleaved Bi₂Sr₂CaCu₂O_8+δ (BSCCO) single crystal with a scanning tunneling microscope reveals a series of repeating terraces, whose separations are then used to identify the atomic planes which are exposed. On each of the exposed planes, the incommensurate modulation is also clearly resolved with atomic resolution. The measured separations between the terraces lead to the deduction that any atomic layer can be exposed by mechanical cleavage of BSCCO. We, therefore, suggest that the identity of atomic planes, and the direction of tunneling, should always be taken into consideration when interpreting tunneling spectra obtained on such cleaved BSCCO crystals.