The orientation-resolved femtosecond spectroscopy, combined with the well-textured (110)- and (001)-Y 0.7 Ca 0.3 Ba 2 Cu 3 O 7-δ thin films, serves as an effective probe to quasiparticle relaxation dynamics on the ab planes and along the diagonal orientations. The significant divergences in the temperature-dependent relaxation time (τ) associated with the opening of superconducting gap were observed along the nodal directions and on the CuO 2 planes which are dominated by the a axis and b axis in the over-doped region. Moreover, the divergence in the temperature-dependent τ along the nodal direction disappears around optimal doped region. This implies that the superconducting gap evolves from the dominant s-wave symmetry in over-doped region into the dominant d-wave symmetry in optimal doped region.
- Anisotropic ultrafast dynamics
- Cuprate superconductors
- Superconducting gap symmetry