IV. Calculation of Electron–Phonon Coupling and Spectral Function for La2-XSrxCuO4, and the Appearance of the d-Wave Pairing

Abstract

We have calculated the k, k′-dependence of the spectral function α2 F(Ω, k, k') using the renormalized one-electron-type band structure obtained in the previous paper III of this series in which the states of carriers and localized spins are separated by the mean field approximation for the localized spins and the latter form a local antiferromagnetic order. It is shown that the electron-phonon interaction which scatter the pairs of electrons from a pair-state (k↑, -k↓) to a different pair-state (k′↑, -k'↓) is repulsive for some combinations of (k, k′) and attractive for other combinations, because of the characteristic feature of the wavefunctions in LSCO in the presence of the local antiferromagnetic order. As a result the spectral function has mainly a d-wave component, and the effective electron-phonon coupling constant for the d-wave pairing, λd, is estimated as 1.96 for x=0.15.