標題: Misfit strain driven cation inter-diffusion across an epitaxial multiferroic thin film interface
作者: Krishnan, P. S. Sankara Rama
Morozovska, Anna N.
Eliseev, Eugene A.
Ramasse, Quentin M.
Kepaptsoglou, Demie
Liang, Wen-I.
Chu, Ying-Hao
Munroe, Paul
Nagarajan, V.
材料科學與工程學系
Department of Materials Science and Engineering
公開日期: 7-二月-2014
摘要: Cation intermixing at functional oxide interfaces remains a highly controversial area directly relevant to interface-driven nanoelectronic device properties. Here, we systematically explore the cation intermixing in epitaxial (001) oriented multiferroic bismuth ferrite (BFO) grown on a (001) lanthanum aluminate (LAO) substrate. Aberration corrected dedicated scanning transmission electron microscopy and electron energy loss spectroscopy reveal that the interface is not chemically sharp, but with an intermixing of similar to 2 nm. The driving force for this process is identified as misfit-driven elastic strain. Landau-Ginzburg-Devonshire-based phenomenological theory was combined with the Sheldon and Shenoy formula in order to understand the influence of boundary conditions and depolarizing fields arising from misfit strain between the LAO substrate and BFO film. The theory predicts the presence of a strong potential gradient at the interface, which decays on moving into the bulk of the film. This potential gradient is significant enough to drive the cation migration across the interface, thereby mitigating the misfit strain. Our results offer new insights on how chemical roughening at oxide interfaces can be effective in stabilizing the structural integrity of the interface without the need for misfit dislocations. These findings offer a general formalism for understanding cation intermixing at highly strained oxide interfaces that are used in nanoelectronic devices. (C) 2014 AIP Publishing LLC.
URI: http://dx.doi.org/10.1063/1.4862556
http://hdl.handle.net/11536/23791
ISSN: 0021-8979
DOI: 10.1063/1.4862556
期刊: JOURNAL OF APPLIED PHYSICS
Volume: 115
Issue: 5
結束頁: 
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