About

    The project is focused on the fundamental condensed matter physics problem of the electromechanical processes scaling in nano-sized ferroelectric materials. Successive development of modern technologies stimulates the decreasing the sizes of the devices and their components, which raises the problem of the size effect influencing on the material properties. The transformation of the piezoelectric properties with the confinement of the objects is characterized by the enhancement of the surface phenomena contribution, decreasing inherent ferroelectric properties due to change of the crystal structure and modification of depolarization field screening conditions. These key phenomena representing intrinsic size effect are essentially entangled with extrinsic size effect caused by the interfaces naturally existing in ferroelectric materials: grain boundaries, domain walls, and phase inhomogeneities.

    Conventional measurement approaches based on the structural analysis are limited to decouple these contributions and predict the functional piezoelectric properties of the nanomaterials. Straightforward scaling of the conventional macroscopic methods for the measurements of the piezoelectric and dielectric properties leads to the natural idea of using atomic force microscopy (AFM) to realize measurement with nanoscale tip. Local measurements of the piezoelectric and dielectric response allow to probe of piezoresponse without contribution from the extrinsic mechanisms and gain a deeper understanding of the contributions from intrinsic and extrinsic size effects. Measurements with a highly non-uniform electric field from AFM tip need deep insight into the methodology with the focus on the emergency of the effects occurring in the probe-surface system. The features of cantilever dynamics, electrostatic tip-sample interaction, and electric field localization should be taken into consideration, which essentially complicates the interpretation of the registered cantilever oscillations and the study of inherent piezoelectric properties of the materials. Thus, separation of the apparent methodological aspects and clarification of local measurements with the piezoresponse force microscopy is important to reliably and quantitatively interpret the local piezoresponse properties.