On the superconducting gap dispersion in hole-doped cuprates

Solutions of the equation for the superconducting gap including superexchange, spin-fluctuation, plasmon, and phonon pairing mechanisms are obtained. Solutions of the Bardeen–Cooper–Schrieffer equation are approximated by the expression $\Delta_{\mathbf{k}}=\Delta_{0}(B\cos(2\phi)+(1-B)\cos(6\phi))$ at a carrier concentration close to optimal. It is found that the dependence proportional to $\cos(6\phi)$ is due to the spin-fluctuation and phononmediated interactions.