LOW-TEMPERATURE SCANNING-TUNNELING-MICROSCOPY AND SPECTROSCOPY OF SINGLE-CRYSTALS OF THE HIGH-TEMPERATURE SUPERCONDUCTOR BI2SR2CACU2O8, CLEAVED IN-SITU AND AT ROOM-TEMPERATURE
A low-temperature scanning tunneling microscope is used for simultaneous topography and superconducting energy gap measurements of Bi2Sr2CaCu2O8+d (Bi2212) single crystals. The samples were cleaved either in situ at 4.2 K or at room temperature with the surface parallel to the a-b planes. The interpretation of the conductance data suggests a superconducting gap value along the c-direction 2 Delta/k(B)T(c) approximate to 9 for the room temperature cleaved crystals and 2 Delta/k(B)T(c) approximate to 6.7 for the low-temperature cleaved samples.