Point-contact spectroscopy of superconducting YBaCuO single crystals of tetragonal modification

The point-contact spectra of tetragonal \(\rm YBa_2Cu_3O_{7-\delta}\) with \(T_c=50-60~K\) are studied at various temperatures. The single-electron energy (\(2\Delta_0/kT_c\simeq 17\)) and its temperature dependence are determined. The characteristic energies of quasiparticle excitations interacting with conduction electrons in this high-\(T_c\). superconductor are found to correlate with the characteristic phonon energies. The possibility of a pair gap, which increases with temperature, is revealed near the critical temperature.