Self-consistent theory of nanodomain formation on nonpolar surfaces of ferroelectrics

Abstract

We propose a self-consistent theoretical approach capable to describe the peculiarities of the anisotropic nanodomain formation induced by a charged AFM probe on non-polar cuts of ferroelectrics. The proposed semi-phenomenological approach accounts for the difference of the threshold fields required for the domain wall motion along non-polar X-and Y -cuts, and polar Z-cut of LiNbO 3 . The effect steams from the fact, that the minimal distance between the equilibrium atomic positions of domain wall and the profile of lattice pinning barrier appeared different for different directions due to the crystallographic anisotropy.Using relaxation-type equation with cubic nonlinearity we calculated the polarization reversal dynamics during the probe-induced nanodomain formation for different threshold field values. The different velocity of domain growth and consequently equilibrium domain sizes on X-, Y-and Z-cuts of LiNbO 3 originate from the anisotropy of the threshold field. Note that the smaller is the threshold field the larger are the domain sizes, and the fact allows explaining several times difference in nanodomain length experimentally observed on X-and Y-cuts of LiNbO 3 . Obtained results can give insight into the nanoscale anisotropic dynamics of polarization reversal in strongly inhomogeneous electric field.

Domain Diversity and Polarization Switching in Amino Acid β-Glycine

“…The polar axes of the investigated crystals were directed along the long side of the crystals and lay in the plane of the substrate. The shape and orientation of β-glycine crystals grown on conductive substrates made it only possible to investigate the domain structure and its evolution during polarization reversal on a nonpolar cut [21,24,26,27] as the polarization is always directed along the longest crystal side.…”

Tailoring of stable induced domains near a charged domain wall in lithium niobate by probe microscopy

“…For domain polarization we applied electric potential to the cantilever relative to earthed substrates with glued-on specimens. Among lithium niobate crystal cuts with a lateral position of the polar axis z, the highest threshold switching field and hence the shortest growing domain were observed in the x-cut crystals [33,34]. Therefore we applied high electric potentials to the cantilever (160 to 200 V).…”

“…Applying electric potential to the microscope cantilever one can locally polarize even ferroelectric materials with a high switching field such as LiNbO 3 . There are multiple indications that ferroelectric domains forming in lithium niobate crystals due to polarization have complex shapes depending on a number of factors: crystallographic orientation of specimen, magnitude and time of voltage application to probe, method of probe movement on specimen surface, electrical conductivity of specimen, surface layer quality and ambient conditions [32][33][34][35][36][37][38]. The complex pattern of domain formation is caused by the fundamental instability of charged domain boundaries forming due to electric potential application to the cantilever: the room temperature electrical conductivity of the crystal is low and the field of the growing domain has not sufficient time for being screened by bulk carriers.…”

Toward High‐Quality Epitaxial LiNbO3 and LiTaO3 Thin Films for Acoustic and Optical Applications

“…The possibility of inverting the domain polarity locally in polycrystalline LN films on SiO 2 /Si, Pt/Si, Si, and indium tin oxide (ITO) on Si substrates by means of PFM and EFM was ( Figure ) demonstrated . During the last decade, the understanding and control of domain inversion in Z‐ , X‐ and Y‐ cut LN single crystals and single crystalline films by focused ion beam and e‐beam writing advanced significantly, and probably these methods will be applied to deposited films in the near future.…”