Measurement of the surface resistance of YBa2Cu3O7−x thin films using stripline resonators

We review methods of measuring surface resistance (R_s) of thin films using stripline resonators, and present our measurements of theR_s of YBa₂Cu₃O_7-x films as a function of frequency, temperature, and r.f. magnetic field. The films were deposited on LaAlO₃ substrates by two methods: (1) electron-beam coevaporation of Y, BaF, and Cu followed by annealing in O₂, and (2) single-targetin situ sputtering. The measurements were obtained at frequencies from 0.4 to 10 GHz, temperatures from 4 to 90 K, and an r.f. magnetic field range from 0 to 30 Oe. At low temperature and low r.f. field at 0.4 GHz, theR_s values obtained for the two deposition methods are approximately 7×10^-6 and 4×10^-6 O, respectively.