Direct observation of asymmetric domain wall motion in a ferroelectric capacitor

Acta Materialia, Volume 61, Issue 18, 2013, Pages 6765-6777.

Ja Kyung Lee, Ga Young Shin, Kyung Song, Woo Seok Choi, Yoon Ah Shin, Seong Yong Park, Jason Britson, Ye Cao, Long-Qing Chen, Ho Nyung Lee, Sang Ho Oh.

 

Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), San 31, Pohang 790-784, Republic of Korea and

Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA and

Analytical Science Group, Samsung Advanced Institute of Technology (SAIT), Yongin 446-712, Republic of Korea and

Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802, USA.

 

Abstract

 

We report in situ transmission electron microscopy observations of the 180° polarization switching process of a PbZr_0.2Ti_0.8O₃ (PZT) capacitor. The preferential, but asymmetric, nucleation and forward growth of switched c-domains were observed at the PZT/electrode interfaces, arising due to the built-in electric field induced at each interface. The subsequent sideways growth of the switched domains was inhibited by the depolarization field due to the imperfect charge compensation at the counter-electrode and also at the boundaries with preexisting a-domains, which contributed further to the asymmetric switching behavior. It was found that the preexisting a-domains split into fine a- and c-domains constituting a 90° stripe domain pattern during the 180° polarization switching process, revealing that these domains also actively participated in the out-of-plane polarization switching. The real-time observations uncovered the origin of the switching asymmetry and further clarified the importance of charged domain walls and the interfaces with electrodes in the ferroelectric switching processes.

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