揭示外延BiFeO₃薄膜混合相区域中的挠曲电效应。

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

作者信息

Cheng Cheng-En, Liu Heng-Jui, Dinelli Franco, Chen Yi-Chun, Chang Chen-Shiung, Chien Forest Shih-Sen, Chu Ying-Hao

机构信息

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.

Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, 30010, Taiwan.

出版信息

Sci Rep. 2015 Jan 28;5:8091. doi: 10.1038/srep08091.

DOI:10.1038/srep08091

PMID:25627445

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC4308693/

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.

摘要

为了解释多铁性材料的奇异行为，理解其纳米尺度相界上的弹性响应是一个至关重要的问题。通过扫描探针显微镜对在LaAlO3(001)衬底上外延生长的混合相BiFeO3薄膜进行了研究，以表征菱面体状单斜相(MI)和倾斜四方状单斜相(MII,tilt)混合相区域中的弹性和压电响应。超声力显微镜显示，低/高刚度值区域在拓扑结构上与MI/MII,tilt相重合。X射线衍射应变分析证实，MI相比MII,tilt相更具柔顺性。值得注意的是，混合相区域内弹性调制与压电响应之间的相关性表明，挠曲电效应导致相界处和MI区域内的压电响应增强。这就解释了应变混合相BiFeO3薄膜中的巨大机电效应。