Two-dimensional electron gas at the PbTi O3/SrTi O3 interface: An ab initio study

Binglun Yin, Pablo Aguado-Puente, Shaoxing Qu, Emilio Artacho

Research output: Contribution to journalArticle

18 Citations (Scopus)

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 nonpolar insulators. In this paper, we substitute the usual, nonferroelectric, 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 PbTiO3/SrTiO3 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 nonvolatile 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.

Original languageEnglish
Article number115406
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume92
Issue number11
DOIs
Publication statusPublished - 08 Sep 2015
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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