FREQUENCY-DEPENDENCE OF THE SURFACE-RESISTANCE IN HIGH-TEMPERATURE SUPERCONDUCTORS

We have measured the surface resistance at 22 GHz, 86 GHz, and 148 GHz of a YBa2Cu3O7 film (5000 Å) deposited on a LaGaO3 substrate. X-ray diffraction data show the film to be highly c-axis and a-axis oriented, and the low values of measured surface resistance suggest that the film is of high quality. In the measured spectral range, the temperature-dependent contribution to the surface resistance is, within experimental error, proportional to the square of the frequency, i.e. Rs ∝ ω2. This result is consistent with various models of loss mechanisms in superconductors. © 1990.