Direct characterization of nanoscale domain switching and local piezoelectric loops of (Pb,La)TiO₃ thin films by piezoresponse force microscopy

〈111〉 and 〈001〉, 〈100〉 preferentially oriented lanthanum-modified lead titanate thin films have been studied at the nanometre scale by means of piezoresponse force microscopy. The nanoscale domain structures, domain switching, and local piezoelectric loops of the films have been analysed. The imaging of the domain structures after the application of a dc field suggests the existence of 90° and 180° domains within the regions with intermediate contrast. The variation of piezoresponse under an electric field in domains of two types has been discussed. Significant differences have been found between the local piezoelectric loops measured in the films deposited on different substrates. These differences are related to the different textures present in the films.