Ferroelectricity and ferromagnetism in EuTiO3nanowires

Abstract

We predicted the ferroelectric-ferromagnetic multiferroic properties of EuTiO 3 nanowires and generated the phase diagrams in coordinates of temperature and wire radii. The calculations were performed within the Landau-Ginzburg-Devonshire theory with phenomenological parameters extracted from tabulated experimental data and first principles calculations. Since bulk EuTiO 3 is antiferromagnetic at temperatures lower than 5.5 K and paraelectric at all temperatures, our goal was to investigate the possibility of inducing the ferroelectric and ferromagnetic properties of EuTiO 3 by reducing the bulk to nanosystems.Our results indicate that ferroelectric spontaneous polarization of ~0.1-0.5C/m 2 is induced in EuTiO 3 nanowires due to the intrinsic surface stress, which is inversely proportional to the nanowire radius. The spontaneous polarization exists at temperatures lower than 300 K, for the wire radius less than 1 nm and typical surface stress coefficients ~ 15 N/m. Due to the strong biquadratic magnetoelectric coupling, the spontaneous polarization in turn induces the ferromagnetic phase at temperatures lower than 30 K for 2 nm nanowire, and at temperatures lower than 10 K for 4 nm nanowire in EuTiO 3 . Thus we predicted that the EuTiO 3 nanowires can be the new ferroelectricferromagnetic multiferroic.

Low-symmetry monoclinic ferroelectric phase stabilized by oxygen octahedra rotations in strained EuxSr1−xTiOMorozovska1, Gu2, Khist3 et al. 2013Phys. Rev. BSelf Cite171191View full textAdd to dashboardCite

“…Magnetic properties of EuTiO 3 at lower temperatures have been discussed elsewhere [24][25][26]38]. Gibbs potential density of Eu x Sr 1-x TiO 3 solid solution as a function of polarization and oxygen octahedra tilt vectors is written as [28]:…”

“…Gibbs potential coefficients are renormalized by the surface tension [28,38], misfit strains [33] and biquadratic coupling between the structural and polar order parameters [30,. The renormalization details are listed in Appendix A, Suppl.…”

New multiferroics based on EuxSr1−xTiO3 nanotubes and nanowires

“…Landau-Ginzburg-Devonshire (LGD) theory Morozovska et al [25] predicted the FE-FM multiferroic properties of EuTiO 3 nanowires originated from the intrinsic surface stress. However, the important impact of the structural AFD order parameter (oxygen octahedron rotations) in EuTiO 3 has not been considered so far.…”

“…Generally, the long-range order appears for sizes larger than the critical sizes (details can be found in Refs. [17][18][19][20]25]). Once the long-range order is established, it is possible to apply the mean field LGD theory [46].…”

“…that appears for the component in the case of nonelectroded tube sidewalls [25]. Schematics of a nanowire.…”