Ferroelectric Dead Layer Driven by a Polar Interface

Abstract

Based on first-principles and model calculations we investigate the effect of polar interfaces on the ferroelectric stability of thin-film ferroelectrics. As a representative model, we consider a TiO2-terminated BaTiO3 film with LaO monolayers at the two interfaces that serve as doping layers. We find that the polar interfaces create an intrinsic electric field that is screened by the electron charge leaking into the BaTiO3 layer. The amount of the leaking charge is controlled by the boundary conditions which are different for three heterostructures considered, namely Vacuum/LaO/BaTiO3/LaO, LaO/BaTiO3, and SrRuO3/LaO/BaTiO3/LaO. The intrinsic electric field forces ionic displacements in BaTiO3 to produce the electric polarization directed into the interior of the BaTiO3 layer. This creates a ferroelectric dead layer near the interfaces that is non-switchable and thus detrimental to ferroelectricity. Our first-principles and model calculations demonstrate that the effect is stronger for a larger effective ionic charge at the interface and longer screening length due to a stronger intrinsic electric field that penetrates deeper into the ferroelectric. The predicted mechanism for a ferroelectric dead layer at the interface controls the critical thickness for ferroelectricity in systems with polar interfaces.

33 Pages, 5 figures

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Cited by in corpus (6)

• Band alignment at metal/ferroelectric interfaces: insights and artifacts from first principles
• Electric-Field-Induced Domain Walls in Wurtzite Ferroelectrics
• Ferroelectricity driven magnetism at domain walls in LaAlO${}_3$/PbTiO${}_3$ superlattices
• Interface control of ferroelectricity in LaNiO3-BaTiO3 superlattices
• Pinned interface dipole-induced tunneling electroresistance in ferroelectric tunnel junctions
• Possible Flexoelectric Origin of the Lifshitz Transition in LaAlO${}_3$/SrTiO${}_3$ Interfaces