Doping dependence of the ultrafast electronic dynamics of Y_1-x Pr_x Ba₂ Cu₃ O₇-δ thin-film superconductors from femtosecond optical spectroscopy

Time-domain spectroscopy, which probes the dynamics of the electronic states near Fermi surface that are associated with superconductivity, has proven to be a powerful method for providing insights into the fundamental nature of both pseudogap and superconducting gap. This study shows that the unique T-x phase diagram with the time-evolving ultrafast dynamics of Y_1-x Pr_x Ba₂ Cu₃ O₇-δ can be used to identify clearly the Nernst, pseudogap, and superconducting regions. All of the orders appear together at a specific delay time, such as 1.2-3 ps, after pumping by an ultrashort pulse. These discoveries suggest that the Nernst effect, the pseudogap and even superconductivity may have the same physical origin.