Interfacial‐Strain‐Controlled Ferroelectricity in Self‐Assembled BiFeO3 Nanostructures. (17th June 2021)

• Record Type: Journal Article
• Authors: Song, Jingfeng; Zhuang, Shihao; Martin, Michael; Ortiz‐Flores, Luis A.; Paudel, Binod; Yarotski, Dmitry; Hu, Jiamian; Chen, Aiping; Huey, Bryan D.
• Is Part Of: Advanced functional materials. Volume 31:Number 34(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-06-17
• Subjects: BiFeO 3‐CoFe 2O 4 -- ferroelectric switching -- interfacial strains -- nanomachining -- tomographic AFM; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.202102311
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract: Self‐assembled BiFeO3 ‐CoFe2 O4 (BFO‐CFO) vertically aligned nanocomposites are promising for logic, memory, and multiferroic applications, primarily due to the tunability enabled by strain engineering at the prodigious epitaxial vertical interfaces. However, local investigations directly revealing functional properties in the vicinity of such critical interfaces are often hampered by the size, geometry, microstructure, and concomitant experimental artifacts. Ferroelectric switching in the presence of lateral distributions of vertical strain thus remains relatively unexplored, with broader implications for all strain‐engineered functional devices. By implementing tomographic atomic force microscopy, 3D domain orientation mapping, and spatially‐resolved ferroelectric switching movies, local tensile strain significantly impacts the ferroelectric switching, principally by retarding domain nucleation in the BFO nearest to the vertically epitaxial tensile‐strained interfaces. The relaxed centers of the BFO pillars become preferred domain nucleation and growth sites for low biases, with up to an order of magnitude change in the edge:center switching ratio for high biases. The new, multi‐dimensional imaging approach—and its corresponding insights especially for directly strained interface effects on local properties—thereby advances the fundamental understanding of polarization switching and provides design principles for optimizing functional response in confined nanoferroic systems. Abstract : Novel 3D ferroelectric domain mapping, alongside spatially resolved ferroelectric switching movies, are achieved via tomographic atomic force microscopy and nanomachining for BiFeO3 nanopillars epitaxially constrained by a CoFe2 O4 matrix. Interfacial strains significantly affect local ferroelectric switching voltages and domain nucleation statistics. Nanoscale volumetric and energetic mapping of heterogeneously strained functional devices can inform future designs of optimized functional nanocomposites and heterostructures.