Microwave conductivity of thin YBCO film in magnetic field

The microwave response of a thin film of high temperature superconductor YBa_2Cu_3O_7 - δ was measured for a wide region of temperatures and magnetic fields. From the measured complex frequency shift, the complex conductivity was calculated. The model for effective conductivity in the mixed state was fitted to the complex conductivity data and the values of upper critical fields B_c2(T) and depinning frequencies ω_0 (T) have been obtained as fitted parameters