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10 June 1996 Carrier relaxation and localisation in Bi2Sr2Ca1-yYyCu2O8 and YBa2Cu3O7-delta : a study by femtosecond time-resolved spectroscopy
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Abstract
Ultrafast time-resolved optical absorption has been measured as a function of doping and temperature in the high temperature superconductors Bi2Sr2Ca1-yYyCu2O8 (0 less than y less than 1) and YBa2Cu3O7-(delta ) (0.06 less than 1). A fast transient response is observed, which changes sign as a function of y in Bi2Sr2Ca1-yYyCu2O8 and in YBa2Cu3O7-(delta ). Careful consideration of the possible mechanisms for the observed behavior lead us to suggest that two independent mechanisms are operating, whereby the two observed positive photoinduced absorption components are due to the electrodynamic response of photoinduced carriers, while the negative signal arises due to spectral hole burning. In the metallic samples a long-lived component is observed, which we suggest comes from photoinduced localized states intrinsic only to the superconducting species of the high-Tc materials. A very significant increase in the scattering rate (1/(tau) ) at temperatures just above Tc signifies coupling to charge and possibly spin fluctuations just above Tc. A large reduction in scattering rate is observed below Tc, similar to that observed previously in YBa2Cu3O6.9 and Tl2Ba2CaCu2O8.
© (1996) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Chris J. Stevens, T. N. Thomas, S. Choudhary, John F. Ryan, Dragan Mihailovic, Laszlo Forro, Gunter A. Wagner, and J. E. Evetts "Carrier relaxation and localisation in Bi2Sr2Ca1-yYyCu2O8 and YBa2Cu3O7-delta : a study by femtosecond time-resolved spectroscopy", Proc. SPIE 2696, Spectroscopic Studies of Superconductors, (10 June 1996); https://doi.org/10.1117/12.241801
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