AbstractWe have measured the surface resistance R, in polycrystalline films of YBCO and BSCCO deposited in our laboratory as well as oriented films made by other laboratories by codepostion techniques. The R, of YBCO and BSCCO has been measured in the frequency range between 0.5 and 40 GHz using a stripline resonator technique. R, for the films is nearly proportional to the square of the applied frequency over the entire measurement range. The magnitude of R, is, however, strongly dependent on the film microstructure. Our measurements at 1 GHz and 4 K show that randomly oriented films have R, ~ 10~3 Ω (close to Cu) while oriented large-grain films have markedly lower R, ~ 2 x 10-6 Ω, approaching the R, of superconducting Nb. The magnitude of R, rises to ~ 2 Ω and ~ 10-3 Ω at 40 GHz for the randomly oriented and preferentially oriented films, respectively. An effective penetration depth, λeff, has been determined from R, using local electrodynamics. We find that λeff is dependent on film microstructure and is ~ 5 µm for high-R, films, decreasing to ~ 5000 Å for low-R, films. The smaller values of Ωeff calculated for oriented films are of similar magnitude to values of the YBCO penetration depth (~ 2000 Å) reported in the literature. The use of the stripline resonator technique for temperature and magnetic field dependent i Measurements of R, will also be discussed.
Erratum: Field-dependent surface resistance for superconducting niobium accelerating cavities [Phys. Rev. Accel. Beams
14
, 101002 (2011)]