Abstract
Two-dimensional (2D) and quasi-2D ferroelectric materials have demonstrated their potential for enabling device miniaturization. The fundamental understanding of the ferroelectric domain structure at atomic scale is limited, however, hindering development of functional device units at the microscopic level. In this paper, we employ a Dion–Jacobson layered oxide (CBNO), which has been predicted to be ferroelectric with high Curie temperature and large in-plane polarization, as a model system to study its ferroelectric domain structure with atomic scale analysis. We reveal the existence of unit-cell-thick ferroelectric domain size as well as both 180° and 90° domain walls in free-standing CBNO. In an epitaxial CBNO film grown on a substrate, we discover multiple stacking structures resembling the Aurivillius and the Ruddlesden–Popper phases. We also analyze the interfacial dislocations and their associated lattice distortion fields in the epitaxial film. This paper may inspire design concepts for ferroelectric devices demanding unit-cell-thick domain size.
- Received 6 October 2020
- Revised 18 February 2021
- Accepted 24 March 2021
DOI:https://doi.org/10.1103/PhysRevMaterials.5.044403
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