Detailed data on the momentum-resolved temperature dependence of the superconducting gap of Bi2Sr2CaCu2O8+x are presented, complemented by similar data on the intensity of the photoemission superconducting condensate spectral area. The gap anisotropy between the Gamma-(M) over bar and Gamma-X directions increases markedly with increasing temperature, contrary to what happens for conventional anisotropic-gap superconductors, such as lead. Specifically, the size of the superconducting gap along the Gamma-X direction decreases to values indistinguishable from zero at temperatures for which the gap retains virtually full value along the Gamma-(M) over bar direction. These data rule out the simplest type of d-wave order parameter.
WOS:A1995QG20700051
1995
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Univ wisconsin,dept phys,madison,wi 53706. univ wisconsin,ctr appl superconduct,madison,wi 53706. ecole polytech fed lausanne,inst phys appl,ch-1015 lausanne,switzerland.
ISI Document Delivery No.: QG207
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