Photoexcited carrier relaxation in a-axis oriented YBa2Cu3O7-delta thin films measured by femtosecond time-resolved spectroscopy

Abstract

The photoexcited carrier relaxation dynamics in a-axis oriented YBa2Cu3O7-delta (YBCO) thin films has been investigated by femtosecond time-resolved spectroscopy. Distinct responses along b-axis (CuO3 chain) and c-axis of YBCO have been separated by the polarization-dependent femtosecond pump-probe measurements. It is found that the transient reflectivity (DeltaR/R) curves for the electric field E of the polarized light parallel to the b- or c-axes of the a-axis oriented YBCO film (Eparallel tob or Eparallel toc) are significantly different. The opening of superconducting gap in CuO3 chain was obviously observed from the measurements of the DeltaR/R curves for Eparallel tob at temperatures below T-c. However, the DeltaR/R curves for Eparallel toc did not exhibit the similar characteristics. (C) 2003 Elsevier Science B.V. All rights reserved.