QUASI-PARTICLE SCATTERING ACROSS THE FERMI-SURFACE IN LA2-XMXCUO4

The strength of pairing of quasiparticles on the Fermi surface is greatly influenced by the phase space for scattering processes for which both initial and final states are required to lie on the Fermi surface. We present calculations of this phase space factor throughout the two dimensional plane based on the local density band structure. We find not only the expected peak at the X point, but also a strong enhancement all along the (110) direction. This behavior can be related to the similarity of the local density Fermi surface to the simple tightbinding model bands discussed previously in many contexts, and indicates possible instabilities which have not heretofore been recognized. © 1990, Elsevier Science Publishers B.V. (North-Holland). All rights reserved.