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Impact of surface water structure on the dynamics of ferroelectric domain walls

Irena Spasojevic,1 Albert Verdaguer,2 Gustau Catalan,1.3 Neus Domingo, 1,4

 1 Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST,  Campus UAB, Bellaterra, 08193 Barcelona, Spain
 2 Institut de Ciència de Materials de Barcelona (ICMAB), CSIC, Campus UAB, Bellaterra, 08193Barcelona, Spain
3ICREA - Institució Catalana de Recerca i Estudis Avançats, 08010 Barcelona, Catalonia

4Current institution: Center for Nanophase Materials Sciences, Oak Ridge National Laboratory,  Oak Ridge, TN 37830, USA

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.  In this context dynamic writing of linear domains in BaTiO3 thin films changes by varying scanning speeds in the range of RH between 2.5% and 60% reveal that the critical speed for domain writing increases non-monotonically with RH.[1] 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 m 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.

Reference(s)

[1] I.Spasojevic, A.Verdaguer, G.Catalan, N.Domingo, Adv. Electron.Mater. (2021), 2100650

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