Stabilization of highly polarized PbTiO3 nanoscale capacitors due to in-plane symmetry breaking at the interface

Stable ferroelectric (FE) phases in nanometer-thick films would enable ultra-high density and fast FE field effect transistors (FeFETs), and the stability of ferroelectricity in ultrathin films has been under intense theoretical and experimental investigation. Here we predict, using density functional theory calculations, that the low-energy epitaxial PbTiO3 (001)/Pt interface strengthens the electrode-oxide bonds by breaking in-plane symmetry and stabilizes a ground state with enhanced polarization in subnanometer oxide films, with no critical-size limit. Additionally, we show that such enhancement is related to large work function differences between the P− and P+ PbTiO3 surfaces, which gives rise to a net polarizing field in the oxide.