Pyroelectric PbSc0.5Ta0.5O3/Y1Ba2Cu3O7−x thin‐film heterostructures

A highly c‐axis oriented PbSc0.5Ta0.5O3/Y1Ba2Cu3O7−x (0.5 μm/0.2 μm) thin‐film heterostructure has been grown in situ on LaAlO3 substrates using a Nd:YAG pulsed laser deposition system. The ferroelectric phase transition in the PbSc0.5Ta0.5O3 thin film is broadened, and suppressed to 195 K with a maximum dielectirc permittivity of emax′ (1 kHz)=950. The observed low loss tangent tan δ=0.063 and high pyroelectric coefficient dP/dT=4.8×10−4 Cm−2 K−1 at 195 K renders PbSc0.5Ta0.5O3 films promising for pyroelectric sensor applications. Furthermore, the dielectric properties are easily controlled by the dc bias electric field E. The field dependence of the reduced polarizability αE2/3 is found to be a universal function of (T/Tc−1)E−2/3 over the wide temperature range 77–300 K. This universal behavior is quantitatively explained in the framework of the Landau mean field theory.