Using high energy resolution angle-resolved photoemission, we have measured both the superconducting gap and the photoemission superconducting condensate spectral area of Bi2Sr2Ca1Cu1O8+x as a function of temperature in two different locations of the Brillouin zone. We found that the size of superconducting gap along the Gamma - X direction decreases to values indistinguishable from zero for which the gap retains virtually full value along the Gamma - (M) over bar direction. The increased gap anisotropy with increasing temperature is in contrast to what happens for conventional anisotropic superconductors such as lead.
Nicola Colonna, Vladimir N. Strocov, Neeraj Kumar
Klaus Kern, Markus Etzkorn, Jacob Senkpiel
Pierluigi Bruzzone, Kamil Sedlák, Nikolay Bykovskiy, Ortensia Dicuonzo