Fig. 2

Momentum dependence of the superconducting gap \(|\Delta (\textbf{k})| = \Delta _0 |\cos k_x - \cos k_y|\) in the Brillouin zone, with \(\Delta _0 \approx 25\) meV. The color scale shows gap magnitude in eV, with d-wave nodes (dark blue, \(\Delta =0\)) along \(k_x = \pm k_y\) and fourfold symmetry.