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Abstract A BiFeO3film is grown epitaxially on a PrScO3single crystal substrate which imparts ~ 1.45% of biaxial tensile strain to BiFeO3resulting from lattice misfit. The biaxial tensile strain effect on BiFeO3is investigated in terms of crystal structure, Poisson ratio, and ferroelectric domain structure. Lattice resolution scanning transmission electron microscopy, precession electron diffraction, and X-ray diffraction results clearly show that in-plane interplanar distance of BiFeO3is the same as that of PrScO3with no sign of misfit dislocations, indicating that the biaxial tensile strain caused by lattice mismatch between BiFeO3and PrScO3are stored as elastic energy within BiFeO3film. Nano-beam electron diffraction patterns compared with structure factor calculation found that the BiFeO3maintains rhombohedral symmetry, i.e., space group ofR3c. The pattern analysis also revealed two crystallographically distinguishable domains. Their relations with ferroelectric domain structures in terms of size and spontaneous polarization orientations within the domains are further understood using four-dimensional scanning transmission electron microscopy technique.
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Crystal Symmetry Engineering in Epitaxial Perovskite Superlattices
Abstract Interface plays a critical role in determining the physical properties and device performance of heterostructures. Traditionally, lattice mismatch, resulting from the different lattice constants of the heterostructure, can induce epitaxial strain. Over past decades, strain engineering has been demonstrated as a useful strategy to manipulate the functionalities of the interface. However, mismatch of crystal symmetry at the interface is relatively less studied due to the difficulty of atomically structural characterization, particularly for the epitaxy of low symmetry correlated materials on the high symmetry substrates. Overlooking those phenomena restrict the understanding of the intrinsic properties of the as‐ determined heterostructure, resulting in some long‐standing debates including the origin of magnetic and ferroelectric dead layers. Here, perovskite LaCoO3‐SrTiO3superlattice (SL) is used as a model system to show that the crystal symmetry effect can be isolated by the existing interface strain. Combining the state‐of‐art diffraction and electron microscopy, it is found that the symmetry mismatch of LaCoO3‐SrTiO3SL can be tuned by manipulating the SrTiO3layer thickness to artificially control the magnetic properties. The work suggests that crystal symmetry mismatch can also be designed and engineered to act as an effective strategy to generate functional properties of perovskite oxides.
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- Award ID(s):
- 1806147
- PAR ID:
- 10361754
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Functional Materials
- Volume:
- 31
- Issue:
- 47
- ISSN:
- 1616-301X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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