  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.
