Effect of Humidity on the Writing Speed and Domain Wall Dynamics of Ferroelectric Domains

Abstract

The switching dynamics of ferroelectric polarization under electric fields depends on the availability of screening charges in order to stabilize the switched polarization. In ferroelectrics, thin films with exposed surfaces investigated by piezoresponse force microscopy (PFM), the main source of external screening charges is the atmosphere and the water neck, and therefore relative humidity (RH) plays a major role. Here, it is shown how the dynamic writing of domains in BaTiO3 thin films changes by varying scanning speeds in the range of RH between 2.5% and 60%. The measurements reveal that the critical speed for domain writing, which is defined as the highest speed at which electrical writing of a continuous stripe domain is possible, increases non‐monotonically with RH. Additionally, the width of line domains shows a power law dependence on the writing speed, with a growth rate coefficient decreasing with RH. The size of the written domains at a constant speed as well as the creep‐factor μ describing the domain wall kinetics follow the behavior of water adsorption represented by the adsorption isotherm, indicating that the screening mechanism dominating the switching dynamics is the thickness and the structure of adsorbed water structure and its associated dielectric constant and ionic mobility.

Understanding piezocatalysis, pyrocatalysis and ferrocatalysis

“…Other known active species include carbonated organic molecules, with different carboxylic groups and Si oxides, or other salts formed from ions contained in the material. So far, the race towards understanding the interplay between ferroelectricity and surface electrochemistry still faces crucial unresolved issues, since at the nanoscale the ferroelectric state is fundamentally inseparable from the electrochemical state of the surface (Yang, Morozovska et al, 2017) and determines ferroelectric switching dynamics (Spasojevic, Verdaguer et al, 2022). This coupling has strong impact on the application of ferroelectric materials in nanodevices such as Tunnel Junctions (Lu, Lipatov et al, 2014;Guo, Wang et al, 2017) since it can create an imprint in the ferroelectric state (Lee, Kim et al, 2016) or alter associated fundamental physical properties such as tunnelling eletroresistance (Gruverman, Wu et al, 2009).…”

Writing‐Speed Dependent Thresholds of Ferroelectric Domain Switching in Monolayer α‐In2Se3

“…As shown in Figure 3d, the threshold voltages were dependent on the writing-speeds, namely the threshold voltage increasing as a function of the writing speed (Figure S7, Supporting Information). This phenomenon can be explained by insufficient surface screening charges capable of stabilizing the newly formed domains at high writing-speed, [21,33] resulting in a system requiring more energy when switched from one state to another. [34] These results were similar to the speeddependent domain wall widths [21] and the simulated electric field distribution under the tip bias.…”

“…This phenomenon can be explained by insufficient surface screening charges capable of stabilizing the newly formed domains at high writing-speed, [21,33] resulting in a system requiring more energy when switched from one state to another. [34] These results were similar to the speeddependent domain wall widths [21] and the simulated electric field distribution under the tip bias. [35][36][37] Thus, successful domain writing with increased speed required a higher PFM tip voltage.…”

“…Some recent experiments suggested that tip writing-speeds could interplay with domain dynamics to alter the nanopatterned domain structures. [20][21][22] However, the study of the interplay between various biased-/loaded-tip writing-speeds and corresponding critical voltages/forces for domain switching is still lacking. Therefore, experimental observation of the effect of biased-/loaded-tip writing-speed on ferroelectric domain switching is highly desirable to clarify the phenomenon.…”

Polar Perturbations in Functional Oxide Heterostructures

“…Specifically, Spasojevic et al showed that the humidity condition plays a crucial role in determining the polarization switching dynamics of ferroelectric materials. [258] Their PFM studies revealed that the speed for domain writing on the surface of BaTiO 3 thin films increased non-monotonically with humidity. For a particular writing speed, the size of the written domains was found to follow water adsorption behavior.…”