Regensburg 2010 – wissenschaftliches Programm
DF 7.2: Vortrag
Dienstag, 23. März 2010, 14:20–14:40, H11
Non-Kolmogorov-Avrami-Ishibashi switching dynamics in nanoscale ferroelectric capacitors — •Yunseok Kim1, Hee Han2, Woo Lee3, Sunggi Baik2, Dietrich Hesse1, and Marin Alexe1 — 1Max Planck Institute of Microstructure Physics, D-06120 Halle (Saale), Germany — 2Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang 790-784, Republic of Korea — 3Korea Research Institute of Standards and Science (KRISS), Daejeon 305-340, Republic of Korea
The electrical polarization in ferroelectrics has two stable states which can be switched by applying an external electric field. The polarization switching mechanisms in macroscopic systems are usually treated within the framework of nucleation and growth theory, i.e. the Kolmogorov-Avrami-Ishibashi (KAI) model. Although there have been many efforts to understand switching dynamics, there is still lack of information on the switching dynamics mostly on nanoscale systems. The switching dynamics of nanoscale capacitors different from their macroscopic counterparts.Moreover, direct studies on nanoscale capacitors remain a challenge. Here we present switching dynamics of nanoscale capacitors with a radius of 35 nm using piezoresponse force microscopy. Polarization switching starts with only one nucleation event occurring only at a pre-determined place. The switching dynamics of nanoscale capacitors do not follow the classical KAI model. Based on the consideration of two separate (nucleation and growth) steps within a non-statistic finite system, we propose a new non-KAI model which is in good agreement with the experimental results.