Ultrafast dynamics in oxygen-deficient Y(0.7)Ca(0.3)Ba(2)Cu(3)O(7-delta) superconductors

Abstract

The transient reflectivity change (Delta R/R) in oxygen-deficient Y(0.7)Ca(0.3)Ba(2)Cu(3)O(7-delta) (YCaBCO) thin films have been systematically measured at various temperatures by femtosecond spectroscopy. The magnitude change of Delta R/R from normal state to superconducting state were clearly observed in YCaBCO with various oxygen deficient, e.g. from overdoped region over optimaldoped region to underdoped region. Additionally, the carrier-phonon coupling strength was also characterized by the relaxation time of Delta R/R at various temperatures and hole concentration.