A tunnelling study of the oxide superconductors La2-xSrxCuO4-yand EuBa2Cu3O7

Abstract
Measurements of the point contact tunnelling spectra of the superconductors La2-xSrxCuO4-y and EuBa2Cu3O7 with Nb were performed. The superconducting gap Delta at 4.2 K with a ratio 2 Delta /Tc of about 10 was obtained. The structure of the tunnelling spectra at voltages above the gap shows that pairing originates from the electron-electron interaction via phonons and possibly via some other excitations of electronic nature with energy about 100 meV.