Temperature dependence of the femtosecond optical response in doped high-temperature superconductors

摘要

Abstract: ent a comprehensive report of time-resolved reflectivity and transmission measurements of the superconducting system Pr$- x$/Y$-1$MIN@x$/Ba$-2$/Cu$-3$/O$-7$MIN$delta$/. For a fixed photon energy (1.98 eV), varying the Pr content permits optical probing of energy states both above and below the Fermi level where a superconducting gap is expected to occur. We find qualitatively different behavior in the sign, magnitude, and temporal responses as a function of Pr fraction. Our results indicate that a simple two-fluid model interpretation cannot account for the observed response and that the intrinsic band structure of Pr$-x$/Y$- 1$MIN@x$/Ba$-2$/Cu$-3$/O$-7$MIN$delta$/ plays a significant role in the dynamics of these systems.!29