Rotational polarization nanotopologies in BaTiO₃/SrTiO₃ superlattices

Abstract

Ferroelectrics are characterized by domain structures as are other ferroics. At the nanoscale though, ferroelectrics may exhibit non-trivial or exotic polarization configurations under proper electrostatic and elastic conditions. These polar states may possess emerging properties not present in the bulk compounds and are promising for technological applications. Here, the observation of rotational polarization topologies at the nanoscale by means of aberration-corrected scanning transmission electron microscopy is reported in BaTiO 3 /SrTiO 3 superlattices grown on cubic SrTiO 3 (001). The transition from a highly homogeneous polarization state to the formation of rotational nanodomains has been achieved by controlling the superlattice period while maintaining compressive clamping of the superlattice to the cubic SrTiO 3 substrate. The nanodomains revealed in BaTiO 3 prove that its nominal tetragonal structure also allows rotational polar textures.

Ferroelectric/paraelectric superlattices for energy storage

“…This type of dipole structure was predicted by first-principles (37), second-principles (like those used in this work) (32), and phase-field (38) simulations and was also experimentally observed (30,39). Similar multidomain states have also been reported for BaTiO 3 /SrTiO 3 superlattices in the past years (40)(41)(42).…”

Ferroelectric/paraelectric superlattices for energy storage

“…This type of dipole structure was predicted by firstprinciples 35 , second-principles 30 (like those used in this work), and phase-field 36 simulations, and was also experimentally observed 28,37 . Similar multidomain states have also been reported for BaTiO 3 /SrTiO 3 superlattices in the past years [38][39][40] .…”

Direct Observation of Large Atomic Polar Displacements in Epitaxial Barium Titanate Thin Films

“…[56,57] Rotational polarization is observed in BTO/STO superlattice because of strain. [58] The reported experimental observed polarization matches theoretical models with biaxial epitaxial strain. To model the large polarization density in the epitaxial BTO film, three different mechanisms for bulk BTO, namely electric field-induced polarization, piezoelectricity (strain-induced polarization) and flexoelectricity (strain gradient-induced polarization), have been considered.…”