SCANNING TUNNELING MICROSCOPY OF THE CLEAVED SURFACE OF BI2SR2CACU2O8

Scanning tunneling microscopy images of the cleaved surface of Bi2 Sr2CaCu2O8 at room temperature have been obtained. Comparison of the dependence of scan line characteristics on tunneling bias with calculations on the density of states of each elemental component around the Fermi energy suggests that tunneling occurs on the Bi face. High resolution images show striations approximately 10 to 30 A wide. On samples oriented with Laue reflection, the striations are observed to run parallel to the a or b axis of the crystal. These striations are likely to be associated with the undulations along the b axis of the Bi layer observed in the bulk in recent transmission electron micrographs. The topographical and tunneling bias dependence results show that the B-rich surface of this new superconductor is essentially a termination of the bulk structure even though structural or chemical defects are common.