Doping dependence of the superconducting gap by Andreev reflection in Au/La2−xSrxCuO4 point-contact junctions Original Research Article

We studied the doping dependence of the superconducting gap in La2−xSrxCuO4 (LSCO) by means of Andreev reflection measurements in Au/LSCO point-contact junctions. The Andreev reflection features were found to disappear at TcA close to the bulk Tc. The fit of the conductance curves with the BTK–Tanaka–Kashiwaya model gives good results if a (s+d)-wave gap symmetry is used. The low-temperature dominant isotropic gap component Δs follows very well the Tc vs. x curve, while the gap-like features observed by angle-resolved photoemission spectroscopy and tunneling scale with T∗. This confirms the different origin of these two energy scales at T