Observation of [110] surface band within {101} a-domain of heteroepitaxial PbTiO3 thin film fabricated by hydrothermal epitaxy

Heteroepitaxial PbTiO3 film on an Nb-doped (001) cubic SrTiO3 substrate was fabricated by hydrothermal epitaxy at 200°C. Piezoresponse force microscopy and x-ray Θ rocking curves confirmed that the film showed a c∕a∕c∕a multi-domain structure even though it did not undergo a cubic paraelectric (PE) to tetragonal ferroelectric (FE) phase transition. After heat treatment of this film at 600°C, we observed the [110] surface band within the a-domain, which was formed through the PE to FE phase transition. We also found that a [110] surface band existed along the (11¯1) plane within the a-domain. We predicted that the [110] surface band would be monoclinic phase due to the interaction of two different variants of a-domains in the presence of a c-domain in the heteroepitaxial PbTiO3 film.