Ferroelastic Nanodomain-mediated Mechanical Switching of Ferroelectricity in Thick Epitaxial Films

Abstract

Mechanical switching of ferroelectric polarization, typically realized via a scanning probe, holds promise in (multi)ferroic device applications. Whereas strain gradientassociated flexoelectricity has been regarded to be accountable for mechanical switching in ultrathin (<10 nm) films, such mechanism can hardly be extended to thicker materials due to intrinsic short operating lengths of flexoelectricity. Here, we demonstrate robust mechanical switching in ∼100 nm thick Pb(Zr 0.2 Ti 0.8 )O 3 epitaxial films with a characteristic microstructure consisting of nanosized ferroelastic domains. Through a combination of multiscale structural characterizations, piezoresponse force microscopy, and phase-field simulations, we reveal that the ferroelastic nanodomains effectively mediate the 180°switching nucleation in a dynamical manner during tip scanning. Coupled with microstructure engineering, this newly revealed mechanism could boost the utility of mechanical switching through extended material systems. Our results also provide insight into competing polarization switching pathways in complex ferroelectric materials, essential for understanding their electromechanical response.

Mechanical Polarization Switching in Hf0.5Zr0.5O2 Thin Film

“…Since the flexoelectric effect was negligibly weak in bulk solid material, epitaxial thin films gain more attention due to induced huge strain gradients . Instead of modulating intrinsic factors that affected flexoelectricity including oxygen vacancy, lattice mismatch, etc., , mechanical polarization switching by using an atomic force microscope (AFM) tip makes the effect more prominent, which has been achieved in several conventional ferroelectrics including BaTiO 3 , BiFeO 3 , LaAlO 3 , LiNbO 3 , PbZr 0.2 Ti 0.8 O 3 , etc. − However, flexoelectric effect in HfO 2 -based materials is rarely reported, , largely narrowing the future applications of HfO 2 -based materials, i.e., nanogenerator, energy harvesting, etc. − …”

Large‐Scale Optical Manipulation of Ferroelectric Domains in PMN‐PT Crystals

“…Although the built‐in electric field caused by photo‐generated carriers dominates the center‐convergent polarization distribution, as to the formation of the ultimate domain patterns, the stress related to the polarization distortion plays an important role, similar to mechanical and electrical manipulation methods. [ 48–50 ]…”

“…Although the built-in electric field caused by photo-generated carriers dominates the center-convergent polarization distribution, as to the formation of the ultimate domain patterns, the stress related to the polarization distortion plays an important role, similar to mechanical and electrical manipulation methods. [48][49][50] In recent years, polar topologies in ferroelectric materials, such as vortices, central domains, skyrmions, etc., have attracted widespread interest due to their novel physical phenomena and properties. [51] Here, we demonstrate for the first time that engineered periodic arrays of center-convergent topological domains are obtained by the optical approach, and the domain patterns are quite stable (Figure S21, Supporting Information).…”

Domain Switching in BaTiO3 Films Induced by an Ultralow Mechanical Force

“…Wen et al and Guo et al have successfully reduced the threshold force by reducing the in-plane compressive strain of thin films. Yuan et al and Li et al confirmed that the polarization reversal barrier can be greatly decreased by a -domain nucleation, making it possible to mechanically induce polarization reversal in thick Pb­(Ti,Zr)­O 3 (PZT) films. Similarly, Lu et al have achieved a wide range of ferroelastic domain switching in 70 nm-thick PbTiO 3 films by adjusting the mismatch strain close to the phase boundary where the c / a and a 1 / a 2 nanodomains coexist.…”