| Abstract Scope |
We have implemented an original constrained occupation Density Functional Theory scheme to mimic the effect of photo-induced thermalized carriers on the structural properties of semiconductors and insulators. We show how these photo-excited carriers may lead to the structural stabilization of higher temperature or new phases in ferroelectric materials such as perovskite titanates, ferroelectric/dielectric superlattices or halogenated perovskites. Thanks to this original scheme, we are able to explore the key control parameters governing the photo-induced response of various materials. For instance, we show through the example of epitaxially strained BiFeO3 that large photostriction, a phenomenon by which mechanical deformations are induced under visible light, can be significantly enhanced at the phase transition boundary between the R- and T-phases. Such enhancement of the photo-induced response stems from the large increase of the piezoelectric constant at the phase boundary. |