Mechanism of superconductivity in cuprates

La2Cu04 by the substitution of trivalent La with divalent Sr, they go into the oxygen p-hole band, and hop from site to site, both directly (with hopping amplitude tpp 0.7 eV) and through an admixture with the d states (r 1 eV). All the cuprates 

Accordingly, at a given value where the is maximum, increasing is accompanied by an increase in T. The observation of a maximum around an optimal value of or Cu-O distance can therefore be traced to the optimal Ajtp value or of the Cu-O charge-transfer energy. 

The a/j-plane dc electrical resistivity of cuprate superconductors above is approximately linear in temperature over a wide range of several hundred degrees (Fig. 7.30). The slopes are nearly the same ( cs 1 cm/K) to within a factor of two for a wide range of single-crystal specimens. The extrapolated zero temperature intercept can be 

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