Reduced Nonlinear Microwave Effects in YBaCuO Resonators on a Polarized $\hbox {SrTiO}_{3}$ Thin Layer

The combination of oxides may yield the elaboration of heterostructures with new or multifunctional properties. With such a philosophy, YBaCuO superconducting thin films were grown on top of a thin SrTiO₃ paraelectric layer to observe the interaction between their respective microwave nonlinearities. The SrTiO₃ layer was characterized by measuring the quality factor (Q ₀) of slot meander line resonators at 6 GHz and 77 K. DC biasing the paraelectric significantly improves the resonator linear and nonlinear response. This paper shows how the saturation of the nonlinear dielectric constant(epsiv_r) and loss tangent (tandelta) in the paraelectric reduces the nonlinearities.