ARPES Study of the Superconducting Gap Anisotropy in Bi_2Sr_2CaCu_2O_8+x

Abstract

We report measurements of the momentum dependence of the superconducting gap in Bi_2Sr_2CaCu_2O_{8+x} (Bi2212) with angle-resolved photoemission spectroscopy using a dense sampling of the Brillouin zone in the vicinity of the Fermi surface. In the Y quadrant of the zone, where there are no complications from ghost bands caused by the superlattice, we find a gap function consistent within error bars to the form cos(k_x)-cos(k_y) expected for a d-wave order parameter. Similar results are found in the X quadrant with the photon polarization chosen to enhance main band emission over that due to ghost bands.

3 pages, revtex, 4 postscript figures