Intrinsic dead layer effects in relaxed epitaxial BaTiO3 thin film grown by pulsed laser deposition

Abstract

Epitaxial BaTiO3 (BT) thin film of about 400 nm thickness was grown on LaSr0.5Co0.5O3 (LSCO) coated (001)MgO using pulsed laser deposition. Ferroelectric properties of the BT thin film in Pt/BT/LSCO/MgO heterostructure capacitor configuration were investigated. Dynamic P-E hysteresis loops at room temperature showed ferroelectric behavior with Ps = 32 μC/cm2, Pr = 14 μC/cm2 and EC = 65 kV/cm. Static C-V measurements confirmed reversible switching with a coercive field EC = 15 kV/cm. Basing on a model taking into account an interface dead-layer we show that the capacitance-voltage “butterfly” loops imply only 25% switching of dipoles that inferred from dynamic polarization-field loops (~ 4 and ~ 16 kV/cm, respectively). Dielectric permittivity as a function of temperature revealed a first-order ferroelectric-to-paraelectric (FE-PE) phase transition in the BT film characterized by a maximum at TC ~ 130 °C. The very large (~ 126 K at 1 kHz) difference between TC and the extrapolated Curie-Weiss temperature T0 is attributed to the dead-layer effects.