fig6

Figure 6. SHG measurements in ferroic superlattices. (A) Integrated SHG intensity as a function of the number of PbTiO₃/SrTiO₃ bilayers in the superlattice. The oscillation between odd and even numbered PbTiO₃ constituents is the signature of destructive interferences between the SHG waves emitted from the ferroelectric layers, hence, of locally reversed polarization in neighboring PTO layers, reprinted with permission from Strkalj et al. Copyright 2022 by the American Physical^[61]. Panel (B) SHG image of a BiFeO₃/TbScO₃ heterostructures evidencing centrosymmetric (antipolar) and usual non-centrosymmetric (polar) domains and SHG intensity angular dependence showing a typical ferroelectric behavior in the non-centrosymmetric areas, reprinted with permission from Caretta et al. Copyright 2022 by the Nature Publishing Group^[62].