Piezoelectric response in SmFe3(BO3)4, a non-piezoactive configuration. The surface piezoelectric effect

An investigation of the mechanisms responsible for the manifestation of the piezoelectric effect in configurations that should not allow for piezoelectric response in the paramagnetic state due to their symmetry. In spite of these symmetry constraints the existence of such a piezoelectric response is detected in this study. It is assumed that these results are associated with the surface on which symmetry constraints are absent. In the magnetically ordered state an indirect piezoelectric effect is both symmetrically permissible and actually observable in these configurations, and it consists of the combined effects of magnetoelectric and magnetoelastic mechanisms.