FAR-INFRARED TRANSMISSION OF YBA2CU3O7-DELTA THIN-FILMS WITH COLUMNARDEFECTS

The far-infrared transmission of YBa2Cu3O7-delta films with columnar d efects 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 trans mission produced by irradiation can be understood by modeling the colu mnar defects as normal-metal or insulating cylinders in a superconduct ing background. Magnetic field induced spectral structure near 60 cm-1 in the pristine samples is suppressed by a defect density equal to th e density of vortices at that field. However, the magneto-transmission above 60 cm-1 is nearly unaffected by the irradiation process. We dis cuss these results in terms of the current understanding of the nature of vortices and columnar defects in YBa2Cu3O7-delta.