Epitaxial heterostructures YBa2Cu3O7−δ/KTaO3 for microwave applications

Combinations of high TC superconducting and ferroelectric films may give rise to tunable, high-Q microwave components. c-axis oriented YBa2Cu3O7−δ films were grown by laser ablation on (001) and vicinically cut KTaO3 substrates and studied by x-ray diffraction and electron microscopy. Competitive superconducting properties were registered. YBa2Cu3O7−δ/KTaO3/YBa2Cu3O7−δ trilayers were deposited on silicon-on-sapphire buffered by CeO2/Y-ZrO2. The dielectric permittivity of KTO3 at 15–100 K decreased considerably when the layer was polarized by a dc voltage. A loss factor tan δ=0.007 was measured at 100 kHz and T=50–100 K.