Two-particle resonance pairing mechanism of oxide superconductivity

The oxide superconductors ${\mathrm{La}}_{2-x}{\mathrm{Sr}}_x\mathrm{Cu}{\mathrm{O}}_4$ and $\mathrm{Y}{\mathrm{Ba}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{6.5+y}$ are treated as strongly correlated electron systems consisting of Cu ions with an on-site electron-electron interaction $U$ of order 10 eV interacting via oxygen bands. Pairing occurs via scattering of quasiparticles into the two-particle resonance at energy $U$. The model is expressed in a slave-boson formalism and solved in mean field. The results explain the observed scaling of $T_c$ with hole concentration and are consistent with other data.