Polarization-dependent conductivity of grain boundaries in BiFeO3 thin films

Charge transport across the interfaces in complex oxides attracts a lot of attention because it allows creating novel functionalities useful for device applications. In particular, it has been observed that movable domain walls in epitaxial BiFeO3 films possess enhanced conductivity that can be used...

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Bibliographic Details
Published in:arXiv.org 2019-06
Main Authors: Alikin, Denis, Fomichov, Yevhen, Saulo Portes Reis, Abramov, Alexander, Chezganov, Dmitry, Shur, Vladimir, Eliseev, Eugene, Morozovska, Anna, Araujo, Eudes, Kholkin, Andrei
Format: Article
Language:English
Subjects:
Bismuth ferrite
Charge simulation
Charge transport
Clusters
Computer simulation
Domain walls
Electrical resistivity
Electronic devices
Ferroelectric materials
Ferroelectricity
Ferroelectrics
Finite element method
Grain boundaries
Polarization
Sol-gel processes
Thermodynamic models
Thin films
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Summary:Charge transport across the interfaces in complex oxides attracts a lot of attention because it allows creating novel functionalities useful for device applications. In particular, it has been observed that movable domain walls in epitaxial BiFeO3 films possess enhanced conductivity that can be used for read out in ferroelectric-based memories. In this work, the relation between the polarization and conductivity in sol-gel BiFeO3 films with special emphasis on grain boundaries as natural interfaces in polycrystalline ferroelectrics is investigated. The grains exhibit self-organized domain structure in these films, so that the "domain clusters" consisting of several grains with aligned polarization directions are formed. Surprisingly, grain boundaries between these clusters (with antiparallel polarization direction) have significantly higher electrical conductivity in comparison to "inter-cluster" grain boundaries, in which the conductivity was even smaller than in the bulk. As such, polarization-dependent conductivity of the grain boundaries was observed for the first time in ferroelectric thin films. The results are rationalized by thermodynamic modelling combined with finite element simulations of the charge and stress accumulation at the grain boundaries giving major contribution to conductivity. The observed polarization-dependent conductivity of grain boundaries in ferroelectrics opens up a new avenue for exploiting these materials in electronic devices.
ISSN:2331-8422