Misfit strain driven cation inter-diffusion across an epitaxial multiferroic thin film interface

Journal Article · Fri Feb 07 04:00:00 EST 2014 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4862556· OSTI ID:22278146

Sankara Rama Krishnan, P. S.; Munroe, Paul; Nagarajan, V. ^[1]; Morozovska, Anna N.; Eliseev, Eugene A. ^[2]; Ramasse, Quentin M.; Kepaptsoglou, Demie ^[3]; Liang, Wen-I.; Chu, Ying-Hao ^[4]

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1. School of Materials Science and Engineering, The University of New South Wales, Sydney, New South Wales 2052 (Australia)
2. Institute of Physics, Institute of Material Sciences, NAS of Ukraine, 03028 Kiev (Ukraine)
3. SuperSTEM laboratory, SciTech Daresbury, Daresbury WA4 4AD (United Kingdom)
4. Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan (China)

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 ∼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.

• OSTI ID: 22278146
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 5 Vol. 115; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALUMINATES
BISMUTH COMPOUNDS
BOUNDARY CONDITIONS
CATIONS
DIFFUSION
DISLOCATIONS
ENERGY-LOSS SPECTROSCOPY
EPITAXY
FERRITES
GINZBURG-LANDAU THEORY
INTERFACES
LANTHANUM COMPOUNDS
POTENTIALS
STRAINS
SUBSTRATES
THIN FILMS
TRANSMISSION ELECTRON MICROSCOPY