Dielectric response of Ba$_{0.05}$Sr$_{0.95}$TiO$_3$(110) films to variations in temperature and electric field

Three-layer epitaxial heterostructures, in which a 1000-nm-thick intermediate layer of Ba$_{0.05}$Sr$_{0.95}$TiO$_3$ is integrated with strontium ruthenate conducting electrodes, have been grown by laser evaporation. Using photolithography and ion etching, film parallel-plate capacitors SrRuO$_3$/Ba$_{0.05}$Sr$_{0.95}$TiO$_3$/SrRuO$_3$ are formed based on the grown heterostructures. A sharp maximum in the temperature dependence of the capacitor capacitance is observed at $T\approx$ 75 K. At $T <$ 100 K, the capacitance decreases by 50–60% upon applying a bias voltage $V_b$ = $\pm$ 2.5 V to the oxide electrodes. The estimate of the specific capacitance ($\sim$ 2.1 $\mu$F/cm$^2$) of the Ba$_{0.05}$Sr$_{0.95}$TiO$_3$(110)/SrRuO$_3$(110) interface is obtained. For $T >$ 250 K and the measuring signal frequency of 1 kHz, the dielectric loss tangent of the film capacitors increases exponentially with increasing temperature.