Spatial dichotomy of quasiparticle dynamics in underdoped thin-film YBa2Cu3O7-delta superconductors

Abstract

By the spatial-temporal-resolved femtosecond spectroscopy on well-textured (110)- and (100)-YBCO thin films, two distinctly temperature-dependent characteristics of quasiparticle relaxation in the nodal and antinodal directions are clearly identified. One temperature dependence associated with a high-energy gap has been observed along the ab diagonal for the whole hole-doping region and along the b axis except near optimal doping, while the other temperature dependence related to the opening of the superconducting gap appears along b axis regardless of the hole concentration. This spatial dichotomy between the nodal and antinodal quasiparticle dynamics and the evolution of gap symmetry with hole doping are discussed for enlightenment on the nature of the phase diagram of hole-doped cuprates. These strongly suggest that the two characteristics may have different physical origins and compete with each other.