Temperature-dependence of the superconducting condensate and gap in Bi2Sr2Ca1Cu2O8+z

Abstract Using high energy resolution angle-resolved photoemission, we have measured both the superconducting gap and the photoemission superconducting condensate spectral area of Bi 2 Sr 2 Ca 1 Cu 1 O 8+ z as a function of temperature in two different locations of the Brillouin zone. We found that the size of superconducting gap along the Γ− X direction decreases to values indistinguishable from zero for which the gap retains virtually full value along the Γ − M direction. The increased gap anisotropy with increasing temperature is in contrast to what happens for conventional anisotropic superconductors such as lead.