Suppressed polar distortion with enhanced Curie temperature in in-plane 90°-domain structure of a-axis oriented PbTiO3 Film

PbTiO3 thin films were epitaxially grown on (001) KTaO3 single crystal substrates by metalorganic chemical vapor deposition. The coherent epitaxial growth introduced a large in-plane tensile strain to the PbTiO3 film. This tensile strain increased TC and directed the polarization to one of the in-plane ⟨100⟩ axes below TC, resulting in the formation of perfect a1/a2/a1/a2 domain structure. We found that the polar distortion is appreciably suppressed in such a1/a2/a1/a2 domain structure while TC is enhanced due to the strain.