Dielectric Properties of a BaTiO₃/REBa₂Cu₃O_y Multilayered Structure for Low-Loss Capacitors

Abstract

A high Q value for resonant circuits is necessary for wireless power transfer. The resistance in the circuit degrades the Q factor; thus, it is important to use elements with a low internal resistance such as superconductors. In this study, we focused on reducing the internal resistance in capacitors by using superconducting electrodes. We fabricated a multilayered structure with epitaxially grown BaTiO₃ films on biaxially oriented YBa₂Cu₃O_y films and measured the superconducting and dielectric properties. As a result, the multilayered film showed superconducting transition at 86.1 K and a large reduction in ESR at temperatures below 90 K. The temperature dependence of the capacitance density peaks at 265 K and coincides with the structural phase transition of BaTiO₃. The relative permittivity ε_r of the multilayered structure was 1.9-23.3, possibly due to a lower crystalline orientation.