Observation of vortex-like excitations in Pr-doped YBCO thin films from femtosecond spectroscopy

The ultrafast dynamics of photoinduced quasiparticles in the (001) Pr-doped YBCO (Y(1-x)Pr(x)Ba(2) Cu(3)O(7-delta), x = 0.1 and 0.2) thin films is revealed by using the femtosecond spectroscopy. Above the zero resistance transition temperature (T(c)), the anomalous rise in the amplitude of the transient reflectivity curves (Delta R/R) were clearly observed. The temperature (T(N)) corresponded to the negative peak in temperature-dependent Delta R/R is well associated with the onset temperature of the anomalous Nernst signal. These ultrafast responses are attributed to vortex-like excitations in the phase incoherent condensate existing above T(c). (C) 2009 Elsevier B.V. All rights reserved.