Appearance of ferroelectricity in BaO nanowires

TL;DR

This paper predicts that high aspect ratio BaO nanowires can exhibit ferroelectricity at room temperature due to intrinsic surface stress, expanding the understanding of ferroelectric behavior in nonferroelectric oxides.

Contribution

The study introduces a theoretical prediction of ferroelectricity in BaO nanowires induced by surface stress, supported by Landau-Ginzburg-Devonshire calculations and first-principles data.

Findings

BaO nanowires with radius 1-10 nm can be ferroelectric at room temperature.

Spontaneous polarization can reach up to 0.5 C/m2.

Surface stress coefficients of 10-50 N/m are sufficient for ferroelectricity.

Abstract

We predict that ferroelectric phase can be induced by the strong intrinsic surface stress inevitably present under the curved surface in the high aspect ratio cylindrical nanoparticles of nonferroelectric binary oxides (BaO, EuO, MgO, etc). We calculated the sizes and temperature range of the ferroelectric phase in BaO nanowires. The analytical calculations were performed within Landau-Ginzburg-Devonshire theory with phenomenological parameters extracted from the first principle calculations [E. Bousquet et al, Strain-induced ferroelectricity in simple rocksalt binary oxides. arXiv:0906.4235v1] and tabulated experimental data. In accordance with our calculations BaO nanowires of radius ~(1-10) nm can be ferroelectric at room temperature (with spontaneous polarization values up to 0.5 C/m2) for the typical surface stress coefficients ~ (10-50) N/m. We hope that our prediction can stimulate both experimental studies of rocksalt binary oxides nanoparticles polar properties as well as the first principle calculations of their spontaneous dipole moment induced by the intrinsic stress under the curved surface.