YBa/sub 2/Cu/sub 3/O/sub 7- delta //LaAlO/sub 3//YBa/sub 2/Cu/sub 3/O/sub 7- delta / trilayer transmission lines for measuring the superconducting penetration depth

Microstrip transmission lines fabricated from two YBa/sub 2/Cu/sub 3/O/sub 7- delta / films separated by a deposited LaAlO/sub 3/ dielectric film provide a technique for measuring the penetration depth. When weakly coupled to a microwave signal, this structure permits precise measurements of the resonant frequencies. The absolute value of the penetration depth as a function of temperature can be calculated from the phase velocity. With this method, there is no need to assume a particular functional form for the temperature dependence. The sensitivities of this method to possible asymmetries in the superconducting film properties and uncertainties in the dielectric constant have also been analyzed. Recently reported microwave measurements are analyzed.<>