  The effects of non-magnetic iso-valent defects inside the CuO2 plane(s) on
superconducting transition temperature, Tc, dc charge transport, and the bulk
magnetic susceptibility, \c{hi}(T), were investigated for the
YBa2(Cu1-yZny)3O7-d (Zn-YBCO) and La2-xSrxCu1-yZnyO4 (Zn-LSCO) superconductors
over a wide range of hole concentrations, p, and Zn contents (y) in the CuO2
plane(s). From the analysis of the \c{hi}(T, y) data, the pseudogap energy
scale, {\epsilon}g, was found to be almost independent of the defect content at
a given value of p. The Zn induced rate of suppression of Tc, dTc(p)/dy, was
found to be strongly p-dependent and showed a systematic variation with hole
concentration, except in the vicinity of p ~ 0.125, i.e., near the so-called
1/8th anomaly where the charge and spin stripe orderings are at their strongest
in various families of hole doped cuprates. Near p ~ 0.125, the static striped
charge ordering is largely believed to dominate the T-p electronic phase
diagram. dTc(p)/dy decreased strongly around this composition, i.e., Zn
abruptly became less effective in degrading Tc when p ~ 0.125. This
observation, together with the facts that (i) Zn suppresses Tc most effectively
and (ii) the characteristic pseudogap energy scale remains insensitive to the
level of Zn substitution, provide us with important clues regarding the nature
and interplay of the underlying electronic correlations present in high-Tc
cuprates. We have discussed the possible connections among the stripe ordering,
superconducting correlations and the pseudogap phenomenon in details in view of
the above findings.
