title: Revealing the flexoelectricity in the mixed-phase regions of epitaxial BiFeO3 thin films.
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 (MI) and tilted tetragonal-like monoclinic (MII,tilt) phases. Ultrasonic force microscopy reveal that the regions with low/high stiffness values topologically coincide with the MI/MII,tilt phases. X-ray diffraction strain analysis confirms that the MI phase is more compliant than the MII,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 MI regions. This accounts for the giant electromechanical effect in strained mixed-phase BiFeO3 films.
authors: 1] Department of Photonics and Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu, 30010, Taiwan [2] Department of Applied Physics, Tunghai University, Taichung, 40704, Taiwan.
authors: Cheng-En
authors: CE
authors: Cheng
authors: Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, 30010, Taiwan.
authors: Heng-Jui
authors: HJ
authors: Liu
authors: Consiglio Nazionale delle Ricerche, Istituto Nazionale di Ottica, I-56124 Pisa, Italy.
authors: Franco
authors: F
authors: Dinelli
authors: Department of Physics, National Cheng Kung University, Tainan, 701, Taiwan.
authors: Yi-Chun
authors: YC
authors: Chen
authors: Department of Photonics and Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu, 30010, Taiwan.
authors: Chen-Shiung
authors: CS
authors: Chang
authors: Department of Applied Physics, Tunghai University, Taichung, 40704, Taiwan.
authors: Forest Shih-Sen
authors: FS
authors: Chien
authors: Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, 30010, Taiwan.
authors: Ying-Hao
authors: YH
authors: Chu
references: Phys Rev Lett. 2012 Dec 14;109(24):247606
references: 23368382
references: Nat Commun. 2011;2:225
references: 21407191
references: Nature. 2000 Jan 20;403(6767):281-3
references: 10659840
references: Adv Mater. 2011 Jul 26;23(28):3170-5
references: 21608053
references: Nanoscale. 2012 Oct 21;4(20):6196-204
references: 22948414
references: Nat Nanotechnol. 2011 Feb;6(2):98-102
references: 21240285
references: Nat Commun. 2013;4:2768
references: 24253399
references: Phys Rev Lett. 2005 Dec 16;95(25):257601
references: 16384507
references: Science. 2009 Nov 13;326(5955):977-80
references: 19965507
references: Phys Rev Lett. 2011 Sep 30;107(14):147602
references: 22107234
references: Adv Mater. 2012 Jun 12;24(22):3070-5
references: 22570278