Nanoscale Bubble Domains and Topological Transitions in Ultrathin Ferroelectric Films
Abstract
Observation of a new type of nanoscale ferroelectric domains, termed as “bubble domains”—laterally confined spheroids of sub‐10 nm size with local dipoles self‐aligned in a direction opposite to the macroscopic polarization of a surrounding ferroelectric matrix—is reported. The bubble domains appear in ultrathin epitaxial PbZr0.2Ti0.8O3/SrTiO3/PbZr0.2Ti0.8O3 ferroelectric sandwich structures due to the interplay between charge and lattice degrees of freedom. The existence of the bubble domains is revealed by high‐resolution piezoresponse force microscopy (PFM), and is corroborated by aberration‐corrected atomic‐resolution scanning transmission electron microscopy mapping of the polarization displacements. An incommensurate phase and symmetry breaking is found within these domains resulting in local polarization rotation and hence impart a mixed Néel–Bloch‐like character to the bubble domain walls. PFM hysteresis loops for the bubble domains reveal that they undergo an irreversible phase transition to cylindrical domains under the electric field, accompanied by a transient rise in the electromechanical response. The observations are in agreement with ab‐initio‐based calculations, which reveal a very narrow window of electrical and elastic parameters that allow the existence of bubble domains. The findings highlight the richness of polar topologies possible in ultrathin ferroelectric structures and bring forward the prospect of emergent functionalities due to topological transitions.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Oct 24, 2017
- Source ID
- 10.1002/adma.201702375
Entities
People
- Alexei Gruverman
- Guangqing Liu
- Laurent Bellaiche
- Lin Xie
- Nagarajan Valanoor
- Qi Zhang
- Sergei Prokhorenko
- Xiaoqing Pan
- Yousra Nahas
Organizations
- Army Research Office
- Australian Research Council
- Defense Advanced Research Projects Agency
- Nanjing University
- National Natural Science Foundation of China
- National Science Foundation
- Semiconductor Research Corporation
- United States Department of Energy
- University of Arkansas
- University of California
- University of Liège
- University of Nebraska–Lincoln
- University of New South Wales