Ferroelectric domain switching in c-axis-oriented epitaxial thin films was studied using different field geometries and compared to numerical simulations and theoretical predictions. With carbon nanotubes as electrodes, continuous nanodomains as small as 9 nm in radius in a 270 nm thick film could be switched, remaining stable for over 20 months. Defect pinning of domain walls appears to play a key role in stabilizing such domains, below the predicted thermodynamic size limit.
REFERENCES
In all three cases, we used a 2D model where the film is modeled by a 270 nm thick and 10 m long rectangle with a relative dielectric permittivity of 80 (measured on the device). The AFM tip was modeled with a high half angle cone terminated by a 50 nm radius disc, the top electrode with a rectangle of 55 nm by 5 m and the CNT with a 1 nm radius disc. The shape and the size of the water meniscus were adapted from Weeks et al.30 and modeled by a Bézier polygon with the same contact angle on the field source and the film.
