Mirror nesting: A superconducting pairing of carriers with a large momentum

The coincidence of Fermi contour portions with isolines of zero kinetic energy of the relative pair motion (the pair Fermi contour) is a necessary condition for superconducting pairing of carriers with a large total pair momentum. In high–$T_c$ cuprates, this situation can occur either due to the formation of a stripe structure or in the absence of the stripe structure when the Fermi contour satisfies the mirror nesting condition. A gradual deviation from this condition leads to a decrease in the superconducting energy gap to zero.