Domain engineering of epitaxial PbTiO3 thin films by the control of misfit strain

Abstract

Ferroelectric domain structures and their evolution in the epitaxial PbTiO3 thin films are greatly affected by the misfit strain and its relaxation during epitaxial film deposition on single crystalline MgO(001) substrates with epitaxial Pt electrode interlayer. The misfit strain could be controlled by varying the underlying interlayer thickness. As the thickness of Pt electrode decreases from 120 urn to 12 nm, the effective lattice constant of Pt electrode increases due to the suppressed generation of misfit dislocations at the Pt(001)/MgO(001) interface. Consequently, the compressive misfit strain in PbTiO3 thin films decreases due to the decreased lattice mismatch with Pt electrode, which enhances the formation of 90degrees domains. Equilibrium domain structures in the epitaxial thin films are also analyzed by the finite element simulation and found to be consistent with the experimental observation. The results manifest that the domain structure and evolution of the epitaxial PbTiO3 thin films could be engineered by the control of misfit strain.