MILLIMETER-WAVE PROPERTIES OF YBA2CU3O7-X FILMS GROWN BY SEVERAL METHODS

The complex conductivities of epitaxial YBa2Cu3O7-x films grown by pulsed laser deposition, off-axis magnetron sputtering and ion-beam sputtering have been determined at 59 GHz from transmission measurements. The temperature dependence of the real part of the measured conductivities differs significantly from the predictions of the two-fluid and BCS theories but the imaginary parts are in good agreement. The BCS model can be brought into agreement with the measurements by allowing the mean-free path to vary with temperature. Surface resistances of 2 m-OMEGA at 82 K and penetration depths, lambda-0, of 175 nm have been determined.