Revealing the flexoelectricity in the mixed-phase regions of epitaxial BiFeO3 thin films

Year: 2015

Authors: Cheng C.E., Liu H.J., Dinelli F., Chen Y.C., Chang C.S., Chien F: S.S., Chu Y.H.

Autors Affiliation: Natl Chiao Tung Univ, Dept Photon, Hsinchu 30010, Taiwan; Natl Chiao Tung Univ, Inst Electroopt Engn, Hsinchu 30010, Taiwan; Tunghai Univ, Dept Appl Phys, Taichung 40704, Taiwan; Natl Chiao Tung Univ, Dept Mat Sci & Engn, Hsinchu 30010, Taiwan; CNR, Ist Nazl Ott, I-56124 Pisa, Italy; Natl Cheng Kung Univ, Dept Phys, Tainan 701, Taiwan.

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.

Journal/Review: SCIENTIFIC REPORTS

Volume: 5      Pages from: 8091-1  to: 8091-5

More Information: This work is supported by Ministry of Science and Technology of Taiwan (Grant NO. MOST 102-2112-M-029-005-MY3), and National Chiao Tung University (2013 NCTU Short-term Research Program Scholarship). The authors would like to thank Dr. P. Pinque of NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore for his kindly support.
DOI: 10.1038/srep08091

Citations: 28
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