FAR-INFRARED TRANSMISSION OF YBA2CU3O7-DELTA THIN-FILMS WITH COLUMNAR DEFECTS

The far-infrared transmission of YBa2Cu3O7-delta films with columnar defects produced by high-energy ion irradiation has been measured from 20 to 150 cm-1 at 6 K in magnetic fields of 0-9 T. The change in transmission produced by irradiation can be understood by modeling the columnar defects as normal-metal or insulating cylinders in a superconducting background. Magnetic field induced spectral structure near 60 cm-1 in the pristine samples is suppressed by a defect density equal to the density of vortices at that field. However, the magneto-transmission above 60 cm-1 is nearly unaffected by the irradiation process. We discuss these results in terms of the current understanding of the nature of vortices and columnar defects in YBa2Cu3O7-delta.