Intrinsic dead layer effects in relaxed epitaxial BaTiO_3 thin film grown by pulsed laser deposition

摘要

Abstract Epitaxial BaTiO3 (BT) thin film of about 400nm 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 P s =32μC/cm2, P r =14μC/cm2 and EC =65kV/cm. Static C-V measurements confirmed reversible switching with a coercive field EC =15kV/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 ~16kV/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 (~126K at 1kHz) difference between TC and the extrapolated Curie-Weiss temperature T0 is attributed to the dead-layer effects. Graphical abstract Display Omitted Highlights • Epitaxial BaTiO3/LaSr0.5Co0.5O3/(001)MgO thin film of about 400 nmthickness grown by PLD. • Calculated Curie-Weiss T0 revealed an abnormal value, attributed to the dead-layer effects in ferroelectric response in BT film. • Effective P r and E c values imply that only 25% of the applied field actually drops across the ferroelectric film.