Polar domains in lead titanate films under tensile strain

TL;DR

This study investigates how tensile strain induces unique polar domain structures in ultrathin PbTiO3 films, revealing low-symmetry phases with potential for high piezoelectric responses, distinct from bulk behavior.

Contribution

It demonstrates the formation of rotated polar domains and low-symmetry phases in strained ultrathin PbTiO3 films, expanding understanding of strain-induced ferroelectric phenomena.

Findings

Polar domains with rotated polarization observed

Low-symmetry phase identified in strained films

Potential for ultrahigh piezoelectric responses

Abstract

Thin films of PbTiO3, a classical ferroelectric, have been grown under tensile strain on single-crystal substrates of DyScO3. The films, of only 5nm thickness, grow fully coherent with the substrate and show no crystallographic twin domains, as evidenced by synchrotron x-ray diffraction. A mapping of the reciprocal space reveals intensity modulations (satellites) due to regularly-spaced polar domains in which the polarization appears rotated away from the substrate normal, characterizing a low symmetry phase not observed in the bulk material. This could have important practical implications since these phases are known to be responsible for ultrahigh piezoelectric responses in complex systems.