Optical conductivity of high-T-c cuprate thin films deposited by multi-target laser ablation

Superconducting cuprate thin films were grown upon MgO single crystals by a lternating laser pulses in controlled sequences upon an insulating MCuO2 ta rget (M = Ca, Sr) and a YBa2Cu3O7-delta (YBCO) target. The infrared conduct ivity of the series of films obtained by this multi-target laser ablation t echnique is deduced from the analysis of infrared reflectivity The method o f fitting by a 'double-damping' Drude model is emphasized and applied to cu prate thin films in a situation in which current Kramers-Kronig analysis is hardly applicable. The agreement of experiment and model is found to be as good as for other conducting oxides investigated previously, including tho se without transition-metal elements. The concentration dependence of the i nfrared conductivity profile is discussed.