1. Condensed Matter Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA

Correspondence to: Ho Nyung Lee¹ Correspondence and requests for materials should be addressed to H.N.L. (Email: hnlee@ornl.gov).

Abstract

Theoretical predictions—motivated by recent advances in epitaxial engineering—indicate a wealth of complex behaviour arising in superlattices of perovskite-type metal oxides. These include the enhancement of polarization by strain^{1, 2} and the possibility of asymmetric properties in three-component superlattices³. Here we fabricate superlattices consisting of barium titanate (BaTiO₃), strontium titanate (SrTiO₃) and calcium titanate (CaTiO₃) with atomic-scale control by high-pressure pulsed laser deposition on conducting, atomically flat strontium ruthenate (SrRuO₃) layers. The strain in BaTiO₃ layers is fully maintained as long as the BaTiO₃ thickness does not exceed the combined thicknesses of the CaTiO₃ and SrTiO₃ layers. By preserving full strain and combining heterointerfacial couplings, we find an overall 50% enhancement of the superlattice global polarization with respect to similarly grown pure BaTiO₃, despite the fact that half the layers in the superlattice are nominally non-ferroelectric. We further show that even superlattices containing only single-unit-cell layers of BaTiO₃ in a paraelectric matrix remain ferroelectric. Our data reveal that the specific interface structure and local asymmetries play an unexpected role in the polarization enhancement.

1. Condensed Matter Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA

Correspondence to: Ho Nyung Lee¹ Correspondence and requests for materials should be addressed to H.N.L. (Email: hnlee@ornl.gov).

MORE ARTICLES LIKE THIS

These links to content published by NPG are automatically generated.