Quantitative Determination of a Microscopic Mechanism of High Tc Superconductivity

Within the t-J model of copper-oxides, the condensation energy can be related to the change in the dynamical spin structure factor between the superconducting and the normal states. By analyzing previous experimental data, we show that the change associated with the resonant neutron scattering peak found in $YBa_2Cu_3O_7$ can quantitatively account for the condensation energy. We argue that this analysis suggests a microscopic mechanism for high Tc superconductivity.