Two-dimensional electron gas at the PbTiO${}_3$/SrTiO${}_3$ interface: an ab initio study

Abstract

In the polar catastrophe scenario, polar discontinuity accounts for the driving force of the formation of a two-dimensional electron gas (2DEG) at the interface between polar and non-polar insulators. In this paper, we substitute the usual, non-ferroelectric, polar material with a ferroelectric thin film and use the ferroelectric polarization as the source for polar discontinuity. We use ab initio simulations to systematically investigate the stability, formation and properties of the two-dimensional free-carrier gases formed in PbTiO${}_3$/SrTiO${}_3$ heterostructures under realistic mechanical and electrical boundary conditions. Above a critical thickness, the ferroelectric layers can be stabilized in the out-of-plane monodomain configuration due to the electrostatic screening provided by the free-carriers. Our simulations also predict that the system can be switched between three stable configurations (polarization up, down or zero), allowing the non-volatile manipulation of the free charge density and sign at the interface. Furthermore, the link between ferroelectric polarization and free charge density demonstrated by our analysis constitutes compelling support for the polar catastrophe model that is used to rationalize the formation of 2DEG at oxide interfaces.

13 pages, 8 figures

References in corpus (8)

• Magnetic effects at the interface between nonmagnetic oxides
• Electric Field Control of the LaAlO${}_3$/SrTiO${}_3$ Interface Ground State
• A polarity-induced defect mechanism for conductivity and magnetism at polar-nonpolar oxide interfaces
• Surface defects and conduction in polar oxide heterostructures
• Oxide Heterostructures for Efficient Solar Cells
• Nanoscale Smoothing and the Analysis of Interfacial Charge and Dipolar Densities
• Oxide superlattices with alternating p and n interfaces
• Model of two-dimensional electron gas formation at ferroelectric interfaces

Cited by in corpus (10)

• First-principles study of two-dimensional electron and hole gases at the head-to-head and tail-to-tail 180${}^{\circ }$ domain walls in PbTiO${}_3$ ferroelectric thin films
• Electrostatics and domains in ferroelectric superlattices
• Polar morphologies from first principles: PbTiO${}_3$ films on SrTiO${}_3$ substrates and the $p(2\times \Lambda )$ surface reconstruction
• Strain-driven sign interchange of surface two-dimensional electron and hole gases in KTaO3 thin film
• Piezoelectric properties of ferroelectric perovskite superlattices with polar discontinuity
• Mechanism for Switchability in Electron-Doped Ferroelectric Interfaces
• The pseudoatomic orbital basis: electronic accuracy and soft-mode distortions in ABO${}_3$ perovskites
• First-principles design of ferromagnetic monolayer MnO${}_2$ at the complex interface
• Magnetic transition and spin-polarized two-dimensional electron gas controlled by polarization switching in strained CaMnO${}_3$/BaTiO${}_3$ slabs
• Piezoelectric properties of II-IV/I-V and II-IV/III-III ferroelectric perovskite superlattices