Relationship between intrinsic surface resistance and critical current density of YBCO thin films with various thickness

We investigated the relationship between the intrinsic surface resistance (R^int_s) and critical current density (J_c) of YBa₂Cu₃Oy (YBCO) film thinner than the penetration depth (k_L). The measured YBCO films were deposited on CeO ₂-buffered r-cut Al₂O₃ substrates by the pulsed laser deposition method. The thicknesses of these films were 300, 200, and 100 nm, respectively. The R^int_s means the surface resistance of YBCO film removing the loss by the impedance of the substrates. The effective surface resistance (Rf) including the impedance of the substrate and the J _c of each YBCO film were measured using the dielectric resonator method at 21.8 GHz and the inductive method. We calculated R^int _s by using phenomenological expressions and the R^eff _s value. The R^int_s values of each YBCO film were almost the same in the measured temperature region. As a result, we found that R^int_s was in inverse proportion to the J_c of YBCO film thinner than λ_L.