Ultrafast quasiparticle dynamics in heavy Ca-doped YBCO thin films

Abstract

The dynamics of photoinduced quasiparticle in the Y(1-x)Ca(x)Ba(2)Cu(3)O(7-delta) thin films is revealed by using the femtosecond reflection spectroscopy. For the case of x = 0.3, two distinct components have been clearly observed in the transient reflectivity change (Delta R/R). The positive component of Delta R/R appears well below T(c). Moreover, the divergent peak of temperature-dependent relaxation time (tau), which is believed to intimately relate to the opening of superconducting gap, shifts to lower temperature as increasing the Ca-doping in YBa(2)Cu(3)O(7-delta). (C) 2010 Elsevier B.V. All rights reserved.