Observation of Dynamic Behavior in YBa₂Cu₃O_7−δ/La_0.88Ca_0.12MnO₃ Using Femtosecond Optical Pulses

Ultrafast pump-optical probe spectroscopy is used to analyze the carrier dynamic behavior in YBa₂Cu₃O_7−δ/La_0.88 Ca_0.12MnO₃ (YBCO/LCMO) heterostructure. The change in reflectivity ΔR/R is induced and is probed by using pulses of 120 fs duration and photon energy 1.55 eV from a Ti:sapphire laser. For higher laser power fluence (such as 0.5 mJ/cm²), the time evolution in transient reflectivity change ΔR/R exhibits three long relaxation processes. We extract the characteristic relaxation time of the different processes by fitting the data and obtain the long characteristic relaxation time which indicates the enhanced proximity effect of the YBCO/LCMO.