Ultrafast pump-probe spectroscopic signatures of superconducting and   pseudogap phases in YBa2Cu3O7-{\delta} films
  Femtosecond pump-probe spectroscopy is applied to identify transient optical signatures of phase transitions in optimally doped YBa2Cu3O7-{\delta} films. To elucidate the dynamics of superconducting and pseudogap phases, the slow thermal component is removed from the time-domain traces of photo-induced reflectivity in a high-flux regime with low frequency pulse rate. The rescaled data exhibit distinct signatures of the phase separation with abrupt changes at the onsets of TSC and TPG in excellent agreement with transport data. Compared to the superconducting phase, the response of the pseudogap phase is characterized by the strongly reduced reflectivity change accompanied by a faster recovery time. 
Chunfeng Zhang, Wei Li, B. Gray, Bin He, Ye Wang, Fan Yang, Xiaoyong   Wang, J. Chakhalian, and Min Xiao
cond-mat.supr-con physics.optics