title: Temperature Dependence of the Superconducting Gap Anisotropy in Bi2Sr2CaCu2O8+x.
abstract: Detailed data on the momentum-resolved temperature dependence of the superconducting gap of Bi(2)Sr(2)CaCu(2)O(8+x) are presented, complemented by similar data on the intensity of the photoemission superconducting condensate spectral area. The gap anisotropy between the Gamma-Mand 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 direction. These data rule out the simplest type of d-wave order parameter.
authors.forename: J
authors.initials: J
authors.lastname: Ma
authors.forename: C
authors.initials: C
authors.lastname: Quitmann
authors.forename: R J
authors.initials: RJ
authors.lastname: Kelley
authors.forename: H
authors.initials: H
authors.lastname: Berger
authors.forename: G
authors.initials: G
authors.lastname: Margaritondo
authors.forename: M
authors.initials: M
authors.lastname: Onellion