Electromechanics of Domain Walls in Uniaxial Ferroelectrics.

Piezoresponse force microscopy (PFM) is used for investigation of the electromechanical behavior of the head‐to‐head (H‐H) and tail‐to‐tail (T‐T) domain walls on the non‐polar surfaces of three uniaxial ferroelectric materials with different crystal structures: LiNbO3, Pb5Ge3O11, and ErMnO3. It is shown that, contrary to the common expectation that the domain walls should not exhibit any PFM response on the non‐polar surface, an out‐of‐plane deformation of the crystal at the H‐H and T‐T domain walls occurs even in the absence of the out‐of‐plane polarization component due to a specific form of the piezoelectric tensor. In spite of their different symmetry, in all studied materials, the dominant contribution comes from the counteracting shear strains on both sides of the H‐H and T‐T domain walls. The finite element analysis approach that takes into account a contribution of all elements in the piezoelectric tensor, is applicable to any ferroelectric material and can be instrumental for getting a new insight into the coupling between the electromechanical and electronic properties of the charged ferroelectric domain walls. [ABSTRACT FROM AUTHOR]