Ion-beam milling of YBCO thin films and their characterization by time-resolved pump-probe method

YBCO films are exposed to Ar ion beams in order to obtain flat surfaces and they are characterized by the time-resolved reflection pump-probe method excited with femtosecond optical pulses. The amplitudes of the reflectivity change of the ion-beam processed films are smaller than that of the as-grown ones and the decay time decreases by the ion-beam etching. These results are discussed in relation to the changes of the supercarrier density and the relaxation time of quasiparticles by the ion-beam milling.