ARPES Study of the Superconducting Gap Anisotropy in Bi_2Sr_2CaCu_2O_8+x

TL;DR

This study uses ARPES to map the momentum dependence of the superconducting gap in Bi-2212, confirming its d-wave symmetry and providing detailed insights into its anisotropy near the Fermi surface.

Contribution

It provides detailed ARPES measurements of the superconducting gap anisotropy in Bi-2212, confirming the d-wave form with high momentum resolution.

Findings

Superconducting gap follows cos(k_x)-cos(k_y) form

Gap anisotropy confirmed near the Fermi surface

Results consistent across different Brillouin zone quadrants

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.