Low temperature scanning tunneling microscopy and spectroscopy of single crystals of the high temperature superconductor Bi 2Sr 2CaCu 2O 8, cleaved “in-situ” and at room temperature

Abstract

A low-temperature scanning tunneling microscope is used for simultaneous topography and superconducting energy gap measurements of Bi 2Sr 2CaCu 2O 8+ 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 Δ/ k B T c–9 for the room temperature cleaved crystals and 2 Δ/ k B T c–6.7 for the low-temperature cleaved samples.