To the problem of electron-phonon interaction and "d-wave pairing" in high-Tc oxides

Abstract

It is supported a recent proposal by Maksimov that electron-phonon interaction (EPI) (Gruneisen-Bloch formulae) determines the linearity of temperature dependence of resistivity for both HTSC-cuprates and most of metals at T near above 0.2 of their characteristic Debye temperature (normal state for HTSC). However, it is emphasized here that in this T-region the resistivity is not proportional to T but is only linear in T. This fact indicates to T-independent contribution to normal-state resistivity in HTSC-cuprates (magnetic contribution, in our treatment) which behavior, in its turn, indicates to possible magnetic (SDW-like) phase transition before SC transition in HTSC-system. SDW-gap (measured as pseudogap with d-wave symmetry, in our treatment) is formed at the symmetrical parts of the Fermi surface above Tc and persists in SC state. The magnitude of SDW-gap is essentially larger than that for SC-gap. So, SDW formed can mimic d-wave symmetry of the order parameter measured below Tc (which is now attributed to d-wave pairing). On the other hand, since the Gruneisen-Bloch curve appears to be (in approach used) a geometric locus for the Tc(onset)(H) (as in LTSC) this fact evidents about EPI-nature (BCS) of SC transition (s-wave) in high-Tc oxides. The proposal to increase Tc using above (SDW/CDW/SC) model (and possible realization) is presented.