Premium
Hierarchical Domain Structure and Extremely Large Wall Current in Epitaxial BiFeO 3 Thin Films
Author(s) -
Bai Zi Long,
Cheng Xiao Xing,
Chen Dong Fang,
Zhang David Wei,
Chen LongQing,
Scott James F.,
Hwang Cheol Seong,
Jiang An Quan
Publication year - 2018
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201801725
Subject(s) - materials science , ferroelectricity , current (fluid) , planar , electrical conductor , polarization (electrochemistry) , thin film , domain wall (magnetism) , conductive atomic force microscopy , domain (mathematical analysis) , electrode , optoelectronics , nanotechnology , condensed matter physics , composite material , atomic force microscopy , magnetic field , computer science , electrical engineering , physics , dielectric , mathematical analysis , chemistry , computer graphics (images) , magnetization , mathematics , quantum mechanics , engineering
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 BiFeO 3 films in a planar‐geometry ferroelectric resistance‐switching memory cell. The engineered films grown on SrTiO 3 and GdScO 3 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.