%0 Journal Article %K superconducting films %K magnetoresistance %K Perovskite %K Manganese %K High temperature superconductors %K Magnetic properties %K Electric conductivity of solids %K Magnetic variables measurement %K Direct current resistivity %K Surface resistances %A S.E Lofland %A M Dominguez %A S.D Tyagi %A S.M Bhagat %A M.C Robson %A C Kwon %A Z Trajanovic %A I Takeuchi %A Ramamoorthy Ramesh %A T Venkatesan %B Thin Solid Films %D 1996 %G eng %P 256-261 %T Surface resistance of thin Perovskite films - High-temperature superconductors and giant magnetoresistance manganites %V 288 %X We present a systematic study of the surface resistance of perovskite thin films and bulk samples at microwave frequencies. The d.c. resistivity p of the various samples spans three orders of magnitude. For bulk samples, we obtain the usual ρ1/2 dependence of Rs. For ρ < 1 μΩ cm, Rs displays conventional behavior, i.e. Rs α ρ. However, for ρ > 1 μΩ cm, Rs is not proportional to ρ but to the conductivity σ. Using this fact, we have made the first direct observation of a peak in σ1, just below Tc in a-axis films of YBa2Cu3O7.