Title: Revealing the flexoelectricity in the mixed-phase regions of epitaxial BiFeO3 thin films
Authors: Cheng, Cheng-En
Liu, Heng-Jui
Dinelli, Franco
Chen, Yi-Chun
Chang, Chen-Shiung
Chien, Forest Shih-Sen
Chu, Ying-Hao
Department of Materials Science and Engineering
Department of Photonics
Issue Date: 28-Jan-2015
Abstract: Understanding the elastic response on the nanoscale phase boundaries of multiferroics is an essential issue in order to explain their exotic behaviour. Mixed-phase BiFeO3 films, epitaxially grown on LaAlO3 (001) substrates, have been investigated by means of scanning probe microscopy to characterize the elastic and piezoelectric responses in the mixed-phase region of rhombohedral-like monoclinic (M-I) and tilted tetragonal-like monoclinic (M-II,M-tilt) phases. Ultrasonic force microscopy reveal that the regions with low/ high stiffness values topologically coincide with the M-I/M-II,M-tilt phases. X-ray diffraction strain analysis confirms that the M-I phase is more compliant than the M-II,(tilt) one. Significantly, the correlation between elastic modulation and piezoresponse across the mixed-phase regions manifests that the flexoelectric effect results in the enhancement of the piezoresponse at the phase boundaries and in the M-I regions. This accounts for the giant electromechanical effect in strained mixed-phase BiFeO3 films.
URI: http://dx.doi.org/10.1038/srep08091
ISSN: 2045-2322
DOI: 10.1038/srep08091
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