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

Abstract

The point-contact spectra of tetragonal $\mathrm{YB}{\mathrm{a}}_2\mathrm{C}{\mathrm{u}}_3{\mathrm{O}}_{7-\delta }$ with $T_c=50-60K$ are studied at various temperatures. The single-electron energy ($2{\Delta }_0/k{T}_c\simeq 17$) 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.

4 pages, 3 figures