High-resolution angle-resolved photoemission spectroscopy of the momentum dependence of the superconducting gap in Bi2Sr2CaCu2O8.

Abstract

The momentum dependence of the superconducting gap in ${\mathrm{Bi}}_{2}$${\mathrm{Sr}}_{2}$Ca${\mathrm{Cu}}_{2}$${\mathrm{O}}_{8}$ has been studied using high-resolution angle-resolved photoemission spectroscopy with nonpolarized light. The size of the superconducting gap obtained at several points on the Fermi surface shows a linear dependence with respect to the gap function of the ${d}_{{x}^{2}\ensuremath{-}{y}^{2}}$ wave defined as $0.5|{cosk}_{x}a\ensuremath{-}{cosk}_{y}a|$. This suggests that the anomaly in the superconducting gap observed with polarized synchrotron-radiation light is not intrinsic, being probably due to the superstructure of the BiO plane, and rather the strong anisotropy of the superconducting gap, like the ${d}_{{x}^{2}\ensuremath{-}{y}^{2}}$ symmetry, is intrinsic.