New theory of superconducting copper oxides—from electronic structure to the d-wave pairing mechanism

Firstly, a brief review is given on recent theoretical developments made by our group as to the many-body effect including electronic structure of hole-doped cuprates. Then the mechanism of superconductivity is discussed on the basis of the above-mentioned electronic structure of LSCO. In doing so we present the results of quantitative calculation of the electron phonon coupling constants and the k, k′ dependence of the spectral function α2F (Ω, k, k′) made on the basis of the renormalized one-electron-type band. The following important results emerge from this calculation: (1) d-wave pairing occurs even for the phonon mechanism, provided the localized spins form a local antiferromagnetie order: (2) phonon modes in which oxygen ions move vertically for CuO2 plane contribute to the electron phonon interaction in cuprates while those like breathing modes in which oxygen and copper ions vibrate within a CuO2 plane do not contribute significantly: (3) the electron phonon interaction in CuO5 pyramid-type cuprates is stronger than CuO6 octahedral-type cuprates.