Twin-boundary dynamics and properties of high-Tc superconductors

We present evidence for collective twin-boundary oscillations in the high-Tc oxide superconductors and propose that their coupling with electrons enhances Tc. These special modes, which we call "dyadons," have a highly anisotropic and low-frequency spectrum, causing the specific heat to change from a T3 temperature dependence to T2 at lower temperatures, consistent with anomalies below 12 K in doped La2CuO4 and in YBa2Cu3O7. The low-frequency dyadons also account for the extended linear temperature dependence of the normal-state resistivity. Due to the unusual anisotropy of both dyadon and electron spectra, vertex corrections generate a strong electron-dyadon coupling at lower temperatures.