Hierarchical domain structure and extremely large wall current in epitaxial BiFeO3 thin films
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Erasable electrical conductive domain walls in an insulating ferroelectric matrix provide novel functionalities for applications in logic and memory devices. The crux of such success requires sufficiently high wall currents to drive high‐speed and high‐power nanodevices. This work provides an appealing strategy to increase the current by two orders of magnitude through the careful selection of current flowing paths along the charged walls. The dense walls come into form through the hierarchical evolution of the 71°, 109°, and 180° domains of epitaxial BiFeO3 films in a planar‐geometry ferroelectric resistance‐switching memory cell. The engineered films grown on SrTiO3 and GdScO3 substrates allow the observation of detailed local configurations and the evolution of the different domain types using vector piezo‐force microscopy. The higher local electrical conductivity near the charged domain walls is identified by conductive atomic‐force microscopy. It is shown that 180° domain reversal proceeds by three‐step 71° rotations of the pristine domains. Surprisingly, a maximum current of ≈300 nA is observed for current paths along charge‐uncompensated head‐to‐head hierarchical domain walls connecting the two electrodes on the film surface. Furthermore, the achievable current level can be conveniently controlled by varying the relative directions of the initial polarization and the applied field.
Long Bai , Z , Cheng , X , Chen , D F , Zhang , D W , Chen , L-Q , Scott , J F , Hwang , C S & Jiang , A Q 2018 , ' Hierarchical domain structure and extremely large wall current in epitaxial BiFeO 3 thin films ' , Advanced Functional Materials , vol. Early View . https://doi.org/10.1002/adfm.201801725
Advanced Functional Materials
© 2018, Wiley-VCH Verlag GmbH & Co KGaA, Weinheim. This work has been made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at https://doi.org/10.1002/adfm.201801725
DescriptionFunding: J.F.S. acknowledges the financial support of the Strategic Priority Research Program of the Chinese Academy of Sciences (grant number XDB07030200).
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